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

Two different kinds of time come through the API, and mixing them up is the most common integration bug. A record date is plain wall-clock text with no zone attached: YYYY-MM-DD, or YYYY-MM-DDTHH:mm when the field carries a time. Each field’s includeTime flag in GET /api/v1/tables tells you which shape to send. The wall these clocks are on is your workspace’s time zone — a shift at 9:00 AM is 9:00 AM at the site, whoever reads it. A timestamp RowFold generates — createdAtUtc, updatedAtUtc, postedAt — is a real instant in UTC, in full ISO 8601. Convert those for display; never convert a record date. Writes are read tolerantly and then normalised. Send 2026-05-18 10:00:00 and it is stored — and returned — as 2026-05-18T10:00. So what you read back may not be byte-identical to what you sent: compare dates by parsing them, never by string equality.