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Calendar Availability

Managing availability to schedule events is one of the most common calendar activities. Nylas provides you with different ways to check availability:

Free/Busy

Free/Busy lets you pass in a time frame and email to return busy times. Free/Busy checks the provider's primary calendar. The email address must be part of the same organization.

Let's look at an example of using /calendars/free-busy for accounts within your organization.

Send a POST request to /calendars/free-busy with the request body :

  • start_time - Unix timestamp for the beginning of the free/busy window.
  • end_time - Unix timestamp for the end of the free/busy window.
  • emails - Email address on the same domain to check. Only one email at a time can be checked. The primary calendar is used to check availability. This works for Microsoft and Gmail accounts.
  • calendars - Use the calendars array to check for other provider types. (Optional)
    • Each account_id represents an individual and supports other providers. Each value in the array for calendar_ids is a unique calendar for that individual.

Free/Busy Request

The examples below show a request with one account and a request with multiple accounts and calendars. You can view shared time slots for different individuals with different providers for multiple accounts and calendars.

curl --request POST \
  --url https://api.nylas.com/calendars/free-busy \
  --header 'Authorization: Bearer <NYLAS_ACCESS_TOKEN>' \
  --header 'Content-Type: application/json' \
  --data '{
  "start_time": "1409594400",
  "end_time": "1409598000",
  "emails": [
    "string"
  ],
  "calendars": [
    {
      "account_id": "3aols9hb9fkqtso7zkzcmwgwv",
      "calendar_ids": [
        "string"
      ]
    }
  ]
}'   
curl --request POST \
  --url https://api.nylas.com/calendars/free-busy \
  --header 'Authorization: Bearer <NYLAS_ACCESS_TOKEN>' \
  --header 'Content-Type: application/json' \
  --data '{
    "start_time": "1633374000",
    "end_time": "1633381200",
    "emails": [
    ],
    "calendars": [
        {
            "account_id": "exampleaccountid1",
            "calendar_ids": [
                "examplecalendaridA",
                "examplecalendaridB"
            ]
        },
        {
            "account_id": "exampleaccountid2",
            "calendar_ids": [
                "examplecalendaridC",
            ]
        }
    ]
}

Free/Busy Response

There are four busy time slots. This means they are free any other time not listed. If there are no busy slots, the request returns an empty time_slots array.

[
    {
        "email": "[email protected]",
        "object": "free_busy",
        "calendar_id": "string",
        "time_slots": [
            {
                "end_time": 1600907400,
                "object": "time_slot",
                "start_time": 1600890568,
                "status": "busy"
            },
            {
                "end_time": 1600961400,
                "object": "time_slot",
                "start_time": 1600959600,
                "status": "busy"
            },
            {
                "end_time": 1600966500,
                "object": "time_slot",
                "start_time": 1600963200,
                "status": "busy"
            },
            {
                "end_time": 1600984800,
                "object": "time_slot",
                "start_time": 1600979400,
                "status": "busy"
            }
        ]
    }
]   

[
    {
        "calendar_id": "examplecalendaridA",
        "email": "[email protected]",
        "object": "free_busy",
        "time_slots": [
            {
                "end_time": 1633379400,
                "object": "time_slot",
                "start_time": 1633377600,
                "status": "busy"
            }
        ]
    },
    {
        "calendar_id": "examplecalendaridB",
        "email": "[email protected]",
        "object": "free_busy",
        "time_slots": [
            {
                "end_time": 1633374900,
                "object": "time_slot",
                "start_time": 1633371300,
                "status": "busy"
            },
            {
                "end_time": 1633383900,
                "object": "time_slot",
                "start_time": 1633380300,
                "status": "busy"
            }
        ]
    },
    {
        "calendar_id": "examplecalendaridC",
        "email": "[email protected]",
        "object": "free_busy",
        "time_slots": [
            {
                "end_time": 1633377600,
                "object": "time_slot",
                "start_time": 1633374000,
                "status": "busy"
            },
            {
                "end_time": 1633377600,
                "object": "time_slot",
                "start_time": 1633374000,
                "status": "busy"
            },
            {
                "end_time": 1633377600,
                "object": "time_slot",
                "start_time": 1633374000,
                "status": "busy"
            }
        ]
    }
]

Free/Busy Empty Time Slots 

[
    {
 "email": "[email protected]",
 "object": "free_busy",
 "time_slots": []
    }
]

Learn More

Review the Free/Busy Status API

How to Create a Calendar Availability Request

There are 2 availability endpoints:

  • /calendars/availability - Check multiple calendars to find available time slots for a single meeting.
  • /calendars/availability/consecutive - Check to find availability for multiple meetings with several participants. Use this endpoint to build itineraries where participants with the same availability are combined.

Each endpoint checks the provider's primary calendar.

The requests to check calendar availability and consecutive availability are made of 3 sections; meeting times, free_busy, and open_hours.

First, you’ll review the 3 main sections of a calendar availability POST request. They consist of:

Then you’ll review the response for calendars/availability and /calendars/availability/consecutive. Finally, there are examples of each showing how you can tailor each request to your needs.

Meeting Time

Meeting time is used to check availability for the specified meeting time between the participants in the emails array. The emails must be in the same organization. The order the emails are entered does not matter.

Create meeting times for both availability and consecutive availability using the request body:

  • duration_minutes - The total number of minutes the event should last.
  • start_time - Unix timestamp for the beginning meeting.
  • end_time - Unix timestamp for the end of the meeting.
  • interval_minutes - How many minutes it should check for availability. For example, if you need to schedule a 30 minute meeting (duration_minutes) and want to check for availability every 10 minutes (interval_minutes).
  • emails - Emails on the same domain to check. If you are using /calendar/availability it accepts an array of emails. If you are using /calendar/consecutive/availability, it accepts a 2D array of emails.

Consecutive Availability 2D Array

When you are using the /consecutive/availability endpoint, emails are entered as a 2D array.

Meeting Time Partial Request Example 

{
    "duration_minutes": 30,
    "start_time": 1600890568,
    "end_time": 1600999200,
    "interval_minutes": 10,
    "emails": [
        "[email protected]",
        "[email protected]"
    ], 
    ...   
{
   "duration_minutes": 30,
   "start_time": 1605794400,
   "end_time": 1605826800,
   "interval_minutes": 10,
   "emails": [
       ["[email protected]", '[email protected]'],
       ['[email protected]']
   ],
...

Checking Multiple Emails
You can pass in up to 50 emails. Since this endpoint uses synchronous requests (one email at a time), this can slow down response times with large requests. You should also keep your provider rate limits in mind.

Free Busy

To check availability for emails not in your organization, you can add them to the free_busy array. Each email address and time slot is its own object. This means if you want to add different busy times for the same email address, you need to add another object for that email address.

Free/Busy works like the free/busy endpoint. You need to know the times the email address outside of your organization is busy. You input these as the start and end times.

Free/Busy is optional for /calendar/availability and /calendar/consecutive/availability. It must still be included as an empty array when not in use.

Create free/busy times for both availability and consecutive availability using the request body:

  • free_busy - A dictionary of free/busy data for users not in your organization. Pass in the emails and times they are busy. Not required as an empty array if checking users in the same organization.
    • email - Email address of guests to check.
    • object - Always free/busy.
      • time_slots - Array containing the start and end times.
        • start_time - Unix timestamp for the beginning of the free/busy window.
        • end_time - Unix timestamp for the end of the free/busy window.
        • object - Always time_slot.
        • status - Always busy.

Free/Busy
Free/Busy is the same for /calendar/availability and /calendar/consecutive/availability.

Free/Busy Partial Request Example 

...
   "free_busy": [
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1601042400,
                   "end_time": 1601044200,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       },
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1601042400,
                   "end_time": 1601044200,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       },
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1601047800,
                   "end_time": 1601051400,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       }
   ]
   ...   
  "free_busy": [
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1605819600,
                   "end_time": 1605821400,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       }
   ],
   ...

Open Hours

Open hours let you combine calendar availability with preferred availability. For example, meeting time will check for open times on the email’s calendar, and adding open hours lets you add additional unavailability.

When creating an open_hours object keep in mind:

  • Open Hours is optional for calendars/availability and calendars/consecutive/availability.
  • Emails added to open hours must all be in the meeting time emails array.
  • Emails not in the organization cannot use open_hours. They should be input using free_busy.

Create open hours for both availability and consecutive availability using the request body:

  • open_hours - Additional times email accounts are unavailable.
  • emails - Emails on the same domain to check. If you are using /calendar/availability it accepts an array of emails. If you are
    using calendar/consecutive/availability, it accepts a 2D array of
    emails.
  • days - The days the participants are not available entered as an integer. Monday corresponds to 0 and Sunday corresponds to 6.
  • timezone - IANA time zone database formatted string (e.g.
    America/New_York).
  • start - Start time in 24 time clock. Leading 0’s are left off. The minimum and maximum start time is 00:00.
  • end - End time in a 24 hour time clock. Leading 0’s are left off. The minimum and maximum end time is 00:00.
  • object_type - Always open_hours.

Open Hours

Open Hours is the same for /calendars/availability and /calendars/consecutive/availability.

...
  "open_hours": [
    {
      "emails": [
        "[email protected]"
      ],
      "days": [
        "0"
      ],
      "timezone": "America/Chicago",
      "start": "10:00",
      "end": "14:00",
      "object_type": "open_hours"
    }
  ]
}   
...
  "open_hours": [
    {
      "emails": [
        [
          "[email protected]"
        ]
      ],
      "days": [
        "0"
      ],
      "timezone": "America/Chicago",
      "start": "10:00",
      "end": "14:00",
      "object_type": "open_hours"
    }
  ]
}

Availability and Consecutive Availability Request

Now that you have gone through each section, you can see the final request for both end points.


{
 "duration_minutes": 30,
 "start_time": 1605794400,
 "end_time": 1605826800,
 "interval_minutes": 10,
 "emails": [
  "[email protected]"
 ],
 "free_busy": [{
  "email": "[email protected]",
  "object": "free/busy",
  "time_slots": [{
   "start_time": 1601042400,
   "end_time": 1601044200,
   "object": "time_slot",
   "status": "busy"
  }]
 }],
 "open_hours": [{
  "emails": [
   "[email protected]"
  ],
  "days": [
   "0"
  ],
  "timezone": "America/Chicago",
  "start": "10:00",
  "end": "14:00",
  "object_type": "open_hours"
 }]
}   

{
  "duration_minutes": 30,
  "start_time": 1605794400,
  "end_time": 1605826800,
  "interval_minutes": 10,
  "emails": [
    [
      "[email protected]"
    ]
  ],
  "free_busy": [
    {
      "email": "[email protected]",
      "object": "free_busy",
      "time_slots": [
        {
          "start_time": 1605819600,
          "end_time": 1605821400,
          "object": "time_slot",
          "status": "busy"
        }
      ]
    }
  ],
  "open_hours": [
    {
      "emails": [
        [
          "string"
        ]
      ],
      "days": [
        "0"
      ],
      "timezone": "America/Chicago",
      "start": "10:00",
      "end": "14:00",
      "object_type": "open_hours"
    }
  ]
}

Availability Response

Once you make your POST request, each endpoint will return availability information.

  • Availability - Returns a list of time slots where all participants are available.
  • Consecutive Availability - Returns all possible groupings that share time slots. If only one person is available, it will return in the response. Use this information to schedule groups of people together for meetings.
{
  "object": "availability",
  "time_slots": [
    {
      "end": 1605803400,
      "object": "time_slot",
      "start": 1605801600,
      "status": "free"
    },
    {
      "end": 1605804000,
      "object": "time_slot",
      "start": 1605802200,
      "status": "free"
    },
    {
      "end": 1605804600,
      "object": "time_slot",
      "start": 1605802800,
      "status": "free"
    },
    {
      "end": 1605805200,
      "object": "time_slot",
      "start": 1605803400,
      "status": "free"
    },
    {
      "end": 1605805800,
      "object": "time_slot",
      "start": 1605804000,
      "status": "free"
    },
    {
      "end": 1605806400,
      "object": "time_slot",
      "start": 1605804600,
      "status": "free"
    },
    {
      "end": 1605807000,
      "object": "time_slot",
      "start": 1605805200,
      "status": "free"
    },
    {
      "end": 1605816000,
      "object": "time_slot",
      "start": 1605814200,
      "status": "free"
    }
  ]
}   
[
  [
    {
      "emails": [
        "[email protected]",
        "[email protected]"
      ],
      "end_time": 1605794400,
      "start_time": 1605792600
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605796200,
      "start_time": 1605794400
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605801600,
      "start_time": 1605799800
    },
    {
      "emails": [
        "[email protected]",
        "[email protected]"
      ],
      "end_time": 1605803400,
      "start_time": 1605801600
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605802200,
      "start_time": 1605800400
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605804000,
      "start_time": 1605802200
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605802800,
      "start_time": 1605801000
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605804600,
      "start_time": 1605802800
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605803400,
      "start_time": 1605801600
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605805200,
      "start_time": 1605803400
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605803400,
      "start_time": 1605801600
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605805200,
      "start_time": 1605803400
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605804000,
      "start_time": 1605802200
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605805800,
      "start_time": 1605804000
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605804000,
      "start_time": 1605802200
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605805800,
      "start_time": 1605804000
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605804600,
      "start_time": 1605802800
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605806400,
      "start_time": 1605804600
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605804600,
      "start_time": 1605802800
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605806400,
      "start_time": 1605804600
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605805200,
      "start_time": 1605803400
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605807000,
      "start_time": 1605805200
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605805200,
      "start_time": 1605803400
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605807000,
      "start_time": 1605805200
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605811200,
      "start_time": 1605809400
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605813000,
      "start_time": 1605811200
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605811800,
      "start_time": 1605810000
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605813600,
      "start_time": 1605811800
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605812400,
      "start_time": 1605810600
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605814200,
      "start_time": 1605812400
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605813000,
      "start_time": 1605811200
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605814800,
      "start_time": 1605813000
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605813000,
      "start_time": 1605811200
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605814800,
      "start_time": 1605813000
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605813600,
      "start_time": 1605811800
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605815400,
      "start_time": 1605813600
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605813600,
      "start_time": 1605811800
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605815400,
      "start_time": 1605813600
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605814200,
      "start_time": 1605812400
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605816000,
      "start_time": 1605814200
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605814200,
      "start_time": 1605812400
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605816000,
      "start_time": 1605814200
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605814800,
      "start_time": 1605813000
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605816600,
      "start_time": 1605814800
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605815400,
      "start_time": 1605813600
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605817200,
      "start_time": 1605815400
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605816000,
      "start_time": 1605814200
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605817800,
      "start_time": 1605816000
    }
  ],
  [
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605826800,
      "start_time": 1605825000
    },
    {
      "emails": [
        "[email protected]"
      ],
      "end_time": 1605828600,
      "start_time": 1605826800
    }
  ]
]

Learn More

Review the Availability APIs.

Collective Meetings

Collective meetings allow for an organizer to host an event with another organizer or an assigned attendee. Attendees can select mutually available time slots for the event. This applies for both internal and external participants. Use the Availability for a Single Meeting endpoint for each of the options.

Check Collective Availability with free_busy

This option uses free_busy object information.

Collective Availability with free_busy Request 

curl --location --request POST 'https://api.nylas.com/calendars/availability' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <ACCESS_TOKEN>' \
--data-raw '{
  "duration_minutes": 15,
  "start_time": 1647889200,
  "end_time": 1647900000,
  "interval_minutes": 5,
  "emails": [
    "[email protected]",
    "[email protected]",
    "[email protected]"
  ],
  "free_busy": [{
    "email": "[email protected]",
    "object": "free_busy",
    "time_slots": [{
      "start_time": 1647889200,
      "end_time": 1647896400,
      "object": "time_slot",
      "status": "busy"
    }]
    },
    {
      "email": "[email protected]",
      "object": "free_busy",
      "time_slots": [{
        "start_time": 1647889200,
        "end_time": 1647896400,
        "object": "time_slot",
        "status": "busy"
      }]
    },
    {
      "email": "[email protected]",
      "object": "free_busy",
      "time_slots": [{
        "start_time": 1647889200,
        "end_time": 1647896400,
        "object": "time_slot",
        "status": "busy"
      }]
    }
  ]
}'

Collective Availability with free_busy Response 

{
    "object": "availability",
    "time_slots": [
        {
            "end": 1647897300,
            "end_time": 1647897300,
            "object": "time_slot",
            "start": 1647896400,
            "start_time": 1647896400,
            "status": "free"
        },
        {
            "end": 1647897600,
            "end_time": 1647897600,
            "object": "time_slot",
            "start": 1647896700,
            "start_time": 1647896700,
            "status": "free"
        },
        {
            "end": 1647897900,
            "end_time": 1647897900,
            "object": "time_slot",
            "start": 1647897000,
            "start_time": 1647897000,
            "status": "free"
        },
        {
            "end": 1647898200,
            "end_time": 1647898200,
            "object": "time_slot",
            "start": 1647897300,
            "start_time": 1647897300,
            "status": "free"
        },
        {
            "end": 1647898500,
            "end_time": 1647898500,
            "object": "time_slot",
            "start": 1647897600,
            "start_time": 1647897600,
            "status": "free"
        },
        {
            "end": 1647898800,
            "end_time": 1647898800,
            "object": "time_slot",
            "start": 1647897900,
            "start_time": 1647897900,
            "status": "free"
        },
        {
            "end": 1647899100,
            "end_time": 1647899100,
            "object": "time_slot",
            "start": 1647898200,
            "start_time": 1647898200,
            "status": "free"
        },
        {
            "end": 1647899400,
            "end_time": 1647899400,
            "object": "time_slot",
            "start": 1647898500,
            "start_time": 1647898500,
            "status": "free"
        },
        {
            "end": 1647899700,
            "end_time": 1647899700,
            "object": "time_slot",
            "start": 1647898800,
            "start_time": 1647898800,
            "status": "free"
        },
        {
            "end": 1647900000,
            "end_time": 1647900000,
            "object": "time_slot",
            "start": 1647899100,
            "start_time": 1647899100,
            "status": "free"
        }
    ]
}

Check Collective Availability from Multiple Providers

This option for collective meetings uses calendars from multiple providers.

Collective Availability from Multiple Providers Request 

curl --location --request POST 'https://api.nylas.com/calendars/availability' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <ACCESS_TOKEN>' \
--data-raw '{
  "duration_minutes": 15,
  "start_time": 1647892800,
  "end_time": 1647907200,
  "interval_minutes": 5,
  "emails": [
    "[email protected]",
    "[email protected]"
    ],
  "free_busy": [],
    "calendars": [
        {
            "account_id": "<ACCOUNT_ID>",
            "calendar_ids": ["<CALENDAR_ID>", "<CALENDAR_ID>"]
        },
        {
            "account_id": "<ACCOUNT_ID>",
            "calendar_ids": ["<CALENDAR_ID>"]
        }
    ]
}'

Collective Availability from Multiple Providers Response 

{
    "object": "availability",
    "time_slots": [
        {
            "end": 1647906300,
            "end_time": 1647906300,
            "object": "time_slot",
            "start": 1647905400,
            "start_time": 1647905400,
            "status": "free"
        },
        {
            "end": 1647906600,
            "end_time": 1647906600,
            "object": "time_slot",
            "start": 1647905700,
            "start_time": 1647905700,
            "status": "free"
        },
        {
            "end": 1647906900,
            "end_time": 1647906900,
            "object": "time_slot",
            "start": 1647906000,
            "start_time": 1647906000,
            "status": "free"
        },
        {
            "end": 1647907200,
            "end_time": 1647907200,
            "object": "time_slot",
            "start": 1647906300,
            "start_time": 1647906300,
            "status": "free"
        }
    ]
}

Check Collective Meetings using Round-Robin with max-availability

This example checks availability for participants in the same organization.

Collective Meetings using Round-Robin with max-availability Request 

curl --location --request POST 'https://api.nylas.com/calendars/availability' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <ACCESS_TOKEN>' \
--data-raw '{
  "duration_minutes": 15,
  "start_time": 1647986400,
  "end_time": 1647993600,
  "interval_minutes": 5,
  "emails": [
    "[email protected]",
    "[email protected]"
    ],
  "free_busy": [],
  "buffer": 30,
  "round_robin": "max-availability",
  "open_hours": [
      {
          "emails": [
              "[email protected]",
              "[email protected]"
          ],
          "days": [
              0,
              1,
              2,
              3,
              4
          ],
          "timezone": "America/Los_Angeles",
          "start": "10:00",
          "end": "16:00",
          "object_type": "open_hours"
      }
  ]
}'

Collective Meetings using Round-Robin with max-availability Response 

{
    "object": "availability",
    "order": [
        "[email protected]",
        "[email protected]"
    ],
    "time_slots": [
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647987300,
            "end_time": 1647987300,
            "object": "time_slot",
            "start": 1647986400,
            "start_time": 1647986400,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647987600,
            "end_time": 1647987600,
            "object": "time_slot",
            "start": 1647986700,
            "start_time": 1647986700,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647987900,
            "end_time": 1647987900,
            "object": "time_slot",
            "start": 1647987000,
            "start_time": 1647987000,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647988200,
            "end_time": 1647988200,
            "object": "time_slot",
            "start": 1647987300,
            "start_time": 1647987300,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647988500,
            "end_time": 1647988500,
            "object": "time_slot",
            "start": 1647987600,
            "start_time": 1647987600,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647988800,
            "end_time": 1647988800,
            "object": "time_slot",
            "start": 1647987900,
            "start_time": 1647987900,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647989100,
            "end_time": 1647989100,
            "object": "time_slot",
            "start": 1647988200,
            "start_time": 1647988200,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647989400,
            "end_time": 1647989400,
            "object": "time_slot",
            "start": 1647988500,
            "start_time": 1647988500,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647989700,
            "end_time": 1647989700,
            "object": "time_slot",
            "start": 1647988800,
            "start_time": 1647988800,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647990000,
            "end_time": 1647990000,
            "object": "time_slot",
            "start": 1647989100,
            "start_time": 1647989100,
            "status": "free"
        }
    ]
}

Check Collective Meetings using Round-Robin with max-fairness

The examples below are for collective meetings using round-robin with max-fairness. This option returns time slots with at least 50% of available participants. Excluded participants are ordered from most recently booked. If max-fairness has no available slots, the results return information from max-availability.

Collective Meetings using Round-Robin with max-fairness Request 

curl --location --request POST 'https://api.nylas.com/calendars/availability' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <ACCESS_TOKEN>' \
--data-raw '{
  "duration_minutes": 15,
  "start_time": 1647986400,
  "end_time": 1647993600,
  "interval_minutes": 5,
  "emails": [
    "[email protected]",
    "[email protected]",
    "[email protected]"
  ],
  "free_busy": [],
  "buffer": 30,
  "round_robin": "max-fairness",
  "open_hours": [
      {
          "emails": [
            "[email protected]",
            "[email protected]",
            "[email protected]"
          ],
          "days": [
              0,
              1,
              2,
              3,
              4
          ],
          "timezone": "America/Los_Angeles",
          "start": "10:00",
          "end": "16:00",
          "object_type": "open_hours"
      }
  ]
}'

Collective Meetings using Round-Robin with max-fairness Response 

{
    "object": "availability",
    "order": [
        "[email protected]",
        "[email protected]"
    ],
    "time_slots": [
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647987300,
            "end_time": 1647987300,
            "object": "time_slot",
            "start": 1647986400,
            "start_time": 1647986400,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647987600,
            "end_time": 1647987600,
            "object": "time_slot",
            "start": 1647986700,
            "start_time": 1647986700,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647987900,
            "end_time": 1647987900,
            "object": "time_slot",
            "start": 1647987000,
            "start_time": 1647987000,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647988200,
            "end_time": 1647988200,
            "object": "time_slot",
            "start": 1647987300,
            "start_time": 1647987300,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647988500,
            "end_time": 1647988500,
            "object": "time_slot",
            "start": 1647987600,
            "start_time": 1647987600,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647988800,
            "end_time": 1647988800,
            "object": "time_slot",
            "start": 1647987900,
            "start_time": 1647987900,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647989100,
            "end_time": 1647989100,
            "object": "time_slot",
            "start": 1647988200,
            "start_time": 1647988200,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647989400,
            "end_time": 1647989400,
            "object": "time_slot",
            "start": 1647988500,
            "start_time": 1647988500,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647989700,
            "end_time": 1647989700,
            "object": "time_slot",
            "start": 1647988800,
            "start_time": 1647988800,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1647990000,
            "end_time": 1647990000,
            "object": "time_slot",
            "start": 1647989100,
            "start_time": 1647989100,
            "status": "free"
        }
    ]
}

Group Meetings

Group meetings involve a single organizer creating an event with multiple invitees and attendees. The organizer sets a single event time and a maximum capacity for attendees.

Use the Create an Event or Update an Event endpoints with the capacity field in the request body. The capacity field defaults to -1 to set no limit on attendees.

If the participant count for the event exceeds the capacity field, Nylas returns a 400 error response with the updated message.

Group Meetings Request Body Example

The capacity field allows for hosts to control the number of attendees and participants for the event. View the sample request body below. If this field isn't included, the default value is -1 for unlimited attendees.

{
    "title": "Fireside Forum",
    "when": {
        "start_time": 1649991600,
        "end_time": 1649995200,
        "start_timezone": "America/Toronto",
        "end_timezone": "America/Toronto"
    },
    "round_robin_order": [],
    "capacity": 5,
    "calendar_id":"<calendar_id>",
    "participants": [
        {
            "email": "<participant email>"
        }
    ]
}

Virtual Calendars

To use Virtual Calendars with Calendar Availability, pass in any events, busy time slots, or times you don't want booked from the Virtual Calendar to the free_busy object.

Learn More

Check out our guide on Virtual Calendar availability.

Availability Examples

Use these examples as a quick reference when making calendar availability requests.

Check Availability in Same Organization

  • /calendars/availability/consecutive requires emails to be entered as a 2D array.
{
    "duration_minutes": 30,
    "start_time": 1600890568,
    "end_time": 1600999200,
    "interval_minutes": 10,
    "emails": [
        "[email protected]",
        "[email protected]"
    ]
}   
{
   "duration_minutes": 30,
   "start_time": 1605794400,
   "end_time": 1605826800,
   "interval_minutes": 10,
   "emails": [
       ["[email protected]"],
       ["[email protected]"]
   ],
   "free_busy": []
}

Check Availability for Accounts Outside the Organization 

{
   "duration_minutes": 30,
   "start_time": 1601042400,
   "end_time": 1601085600,
   "interval_minutes": 10,
   "emails": [
       "[email protected]",
       "[email protected]"
   ],
   "free_busy": [
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1601042400,
                   "end_time": 1601044200,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       },
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1601042400,
                   "end_time": 1601044200,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       },
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1601047800,
                   "end_time": 1601051400,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       }
   ]
}   
{
   "duration_minutes": 30,
   "start_time": 1605794400,
   "end_time": 1605826800,
   "interval_minutes": 10,
   "emails": [
       ["[email protected]"],
       ["[email protected]"]
   ],
   "free_busy": [
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1605819600,
                   "end_time": 1605821400,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       }
   ]
}

Check Availability with Open Hours

  • Accounts outside the organization are entered in the free_busy array.
  • /calendars/availability/consecutive requires emails to be entered as a 2D array.
  • Open hours are optional when checking availability.
{
   "duration_minutes": 30,
   "start_time": 1605794400,
   "end_time": 1605826800,
   "interval_minutes": 10,
   "emails": [
       "[email protected]",
       "[email protected]",
       "[email protected]"
   ],
   "free_busy": [
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1605819600,
                   "end_time": 1605821400,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       }
   ],
   "open_hours": [
       {
           "emails": [
         "[email protected]",
         "[email protected]",
           ],
           "days": [
               0,
               1,
               2,
               3,
               4,
               5,
               6
           ],
           "timezone": "America/Chicago",
           "start": "10:00",
           "end": "14:00",
           "object_type": "open_hours"
       }
   ]
}   
{
   "duration_minutes": 30,
   "start_time": 1605794400,
   "end_time": 1605826800,
   "interval_minutes": 10,
   "emails": [
       ["[email protected]"],
       ["[email protected]"]
   ],
   "free_busy": [
       {
           "email": "[email protected]",
           "object": "free_busy",
           "time_slots": [
               {
                   "start_time": 1605819600,
                   "end_time": 1605821400,
                   "object": "time_slot",
                   "status": "busy"
               }
           ]
       }
   ],
   "open_hours": [
       {
           "emails": [
               "[email protected]"
           ],
           "days": [
               0,
               1,
               2,
               3,
               4,
               5,
               6
           ],
           "timezone": "America/Chicago",
           "start": "10:00",
           "end": "14:00",
           "object_type": "open_hours"
       }
   ]
}

Check for Free/Busy

  • Can only check accounts within your organization.
{
 "start_time":"1600890568",
 "end_time":"1600999200",
 "emails": ["[email protected]"]
}{
 "start_time":"1600890568",
 "end_time":"1600999200",
 "emails": ["[email protected]"]
}

Round-Robin

You can use round-robin scheduling to check availability for a single meeting.

Round-robin accepts:

  • null
  • max-availability
  • max-fairness

Null

Will return times when everyone is available.

Max Availability

Max availability will return all time slots where at least one person specified in free_busy, calendars, or emails is available.

Max Availability Request Example

The example below shows a list of available timeslots for a single person along with the list of configured participants.

curl --request POST \
  --url https://api.nylas.com/calendars/availability \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer <ACCESS_TOKEN>' \
  --header 'Content-Type: application/json' \
  --data '{
    "duration_minutes": 60,
    "interval_minutes": 60,
    "start_time": 1634734800,
    "end_time": 1634749200,
    "emails": [],
    "free_busy": [],
    "round_robin": "max-availability",
    "calendars": [
        {
            "account_id": "exampleaccountid1",
            "calendar_ids": [
                "examplecalendaridA",
                "examplecalendaridB"
            ]
        },
        {
            "account_id": "exampleaccountid2",
            "calendar_ids": [
                "examplecalendaridC",
            ]
        }
    ]
}

Max Availability Response Example

This response includes the order of emails for a timeslots with multiple emails. The suggestions are preferences based on the most recently created event.

{
    "object": "availability",
    "order": [
        "[email protected]",
        "[email protected]"
    ],
    "time_slots": [
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1634738400,
            "object": "time_slot",
            "start": 1634734800,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]",
                "[email protected]"
            ],
            "end": 1634742000,
            "object": "time_slot",
            "start": 1634738400,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]"
            ],
            "end": 1634745600,
            "object": "time_slot",
            "start": 1634742000,
            "status": "free"
        },
        {
            "emails": [
                "[email protected]"
            ],
            "end": 1634749200,
            "object": "time_slot",
            "start": 1634745600,
            "status": "free"
        }
}

Max Fairness

Max fairness will return time slots where the least recently booked 50% of people are available. Max fairness defaults to max-availability if no time slots are found. Max fairness is calculated using the round_robin_order from Create Event.

To use max-fairness you need to create a new event with an array of emails in round_robin_order.
s

Consecutive Availability Meeting Parameter

The /calendars/availability/consecutive accepts a parameter, meetings. Meetings allow an organizer to see consecutive meeting times with breaks in between.

Available Times for Consecutive Meetings

To find meeting times add the meetings array. It will look for meetings times that match and are consecutive between each group of emails. You can also specify meeting length by adding duration_minutes.

{
 "start_time": 1633374000,
 "end_time": 1633381200,
 "interval_minutes": 15,
 "free_busy": [{
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": [{
    "status": "busy",
    "start_time": 300,
    "object": "time_slot",
    "end_time": 1699
   }]
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  }
 ],
 "meetings": [{
   "emails": [
    "[email protected]",
    "[email protected]",
    "[email protected]"
   ],
   "duration_minutes": 45
  },
  {
   "emails": [
    "[email protected]",
    "[email protected]"
   ],
   "duration_minutes": 15
  },
  {
   "emails": [
    "[email protected]"
   ]
  },
  {
   "emails": [
    "[email protected]"
   ]
  }
 ]
}

Available Time with Gaps

The following code sample will look for meetings that have time slots between them. To specify time between meetings, pass in an empty emails array with duration_minutes. The duration_minutes will indicate the time between the meetings.

{
 "start_time": 1633374000,
 "end_time": 1633381200,
 "interval_minutes": 15,
 "free_busy": [{
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": [{
    "status": "busy",
    "start_time": 300,
    "object": "time_slot",
    "end_time": 1699
   }]
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  },
  {
   "object": "free_busy",
   "email": "[email protected]",
   "time_slots": []
  }
 ],
 "meetings": [{
   "emails": [
    "[email protected]",
    "[email protected]",
    "[email protected]"
    "duration_minutes": 10
   ]
  },
  {
   "emails": [
    "[email protected]",
    "[email protected]",
    "duration_minutes": 5
   ]
  },
  {
   "emails": [
    "[email protected]"
   ]
  },
  {
      "emails": [],
      "duration_minutes": 5,
  }
 ]
}

Meetings Array Limitations

There are a few things to keep in mind when adding meetings.

  • If meetings.emails is present, then the emails is ignored.

  • If meetings.duration_minutes is present, then duration_minutes is ignored.

    {
    "start_time": 1633374000,
    "end_time": 1633381200,
    "duration_minutes": 30, // This duration integer is ignored, if meetings.duration_minutes are added.
    "interval_minutes": 15,
      "emails": [
        ["[email protected]", "[email protected]"], // This emails array is ignored, if meetings.emails are added. 
      ],
    "free_busy": [{
      "object": "free_busy",
      "email": "[email protected]",
      "time_slots": []
      },
      {
      "object": "free_busy",
      "email": "[email protected]",
      "time_slots": [{
        "status": "busy",
        "start_time": 300,
        "object": "time_slot",
        "end_time": 1699
      }]
      },
      {
      "object": "free_busy",
      "email": "[email protected]",
      "time_slots": []
      },
      {
      "object": "free_busy",
      "email": "[email protected]",
      "time_slots": []
      },
      {
      "object": "free_busy",
      "email": "[email protected]",
      "time_slots": []
      },
      {
      "object": "free_busy",
      "email": "[email protected]",
      "time_slots": []
      }
    ],
    "meetings": [{
      "emails": [
        "[email protected]",
        "[email protected]",
        "[email protected]"
        "duration_minutes": 10
      ]
      },
      {
      "emails": [
        "[email protected]",
        "[email protected]",
        "duration_minutes": 5
      ]
      },
      {
      "emails": [
        "[email protected]"
      ]
      },
      {
          "emails": [],
          "duration_minutes": 5,
      }
    ]
    }

  • The response will return a minimum of 1 and a maximum of 10,000.

  • The maximum number of meeting is 500.

  • If meeting.duration_minutes is used, then duration_minutes is ignored.

  • If meeting.emails is used, then emails is ignored.

  • If meetings.emails is empty, but duration_minutes is present, then it is treated as a meeting gap.

  • Meeting gaps are not scheduled:

    • At the start of the meeting
    • The end of the meeting
    • Next to another gap

Comparison of Availability Endpoints

If you are not sure which to use, review the functionality of the endpoint.

When to Use Availability

  • Need to check availability for multiple participants and organize
    itineraries.
  • Some participants are outside your organization.
    • You will need to know when they are busy.
  • Need to check for specific event duration and intervals. You want to set additional unavailable times that are not on the calendar.

When to Use Free or Busy

  • Only need to check one email address.
  • The account is added to your Nylas application. Free/Busy can only check accounts within your organization.
  • You only need to know if someone is busy and don’t need to know if their schedule aligns with another email address.

Feature Support

Endpoint Scopes Provider Availability SDK Support Feature Availability
Availability calendar
calendar.read_only		 Microsoft
Google		 Python - Open Hours is not supported. Availability does support Room Resources. Just treat it as an email address when checking availability.
Consecutive Availability calendar
calendar.read_only		 Microsoft
Google		 None Consecutive Availability does support Room Resources. Just treat it as an email address when checking availability.
Free/Busy calendar
calendar.read_only		 Microsoft
Google		 Python
Java
Node		 Free/Busy does not support Virtual Calendars.

Free/Busy does not support Room Resources.

What's Next?