The REST API, API clients, and webhooks — Sending dates through the API (2)

Two things are refused with a 400 naming the field, rather than stored: • Text that isn’t a date. Storing it would leave a column no date filter can ever match, and you’d find out weeks later. • A date carrying a zone — 2026-05-18T09:00Z, 2026-05-18T09:00+01:00. An offset turns the value into an instant, and turning an instant back into wall-clock time is a guess RowFold won’t make on your behalf. Convert to the workspace’s local time and send the bare form. Parse tolerantly on the way out, too: turning Include a time off in the app never strips times already stored, so a date-only column can still hand you a timed value from before the change.