Dates and times

The Asana API uses the ISO 8601 date time format for endpoints that return or accept date and time values.

Date-only values

For values that are dates without a time, such as a task's due_on field, the format will be the date-only ISO 8601 format YYYY-MM-DD.

Date and time values

The ISO 8601 format YYYY-MM-DDTHH:mm:ss:fffZ is used for fields that return or accept date and time values.

Date PartDescription
YYYYFour-digit year (e.. 2024)
MMTwo-digit month (01 = January, 02 = February, ..., 12 = December)
DDTwo-digit day of the month (01 through 31)
TSeparator indicating the start of the time component
HHTwo-digit hour in 24-hour format (00 through 23)
mmTwo-digit minute (00 through 59)
SSTwo-digit second (00 through 59)
fffThree-digit fractional seconds (000 through 999)
ZIndicates Coordinated Universal Time (UTC)


  • A task's due_on field may return a date-only value such as 2024-05-27. This value represents May 27, 2024.
  • A task's created_at field may return a value such as 2024-05-24T19:50:18.053Z. This value represents May 24, 2024, at 7:50 PM UTC, plus 18 seconds and a fractional value of 0.053 seconds.

API Query example

Some API endpoints accept a date/time value as a query param. One example is the GET /tasks endpoint that accepts a modified_since query param to filter tasks that have changed since a given date/time. To query tasks in the project with an GID of 123456 that have been modified since May 24, 2024 at 4:00 PM UTC, the API call would look like the following.