Dates and times
Timestamps
Section titled “Timestamps”Timestamps (string <date-time>), for example created_at, updated_at,
completed_at or last_active, are returned by the API in ISO 8601 format without a
time zone designator: YYYY-MM-DDThh:mm:ss.
"2026-01-11T09:25:16"All timestamps are in German time (time zone Europe/Berlin, that is CET or CEST) and truncated to whole seconds; fractional seconds are not returned.
The same format applies to timestamps you send to the API (for example
email_scheduled_at when creating a participation). A timestamp without a time zone
designator is interpreted as German time. Alternatively, you can include an ISO 8601
offset (for example "2026-06-01T08:00:00Z" or "2026-06-01T10:00:00+02:00"); the API
converts such values to German time.
Dates (string <date>), for example due_date or birth_date, use the format
YYYY-MM-DD:
"2026-12-31"