Update the fields of a single lead.

When to use. Change one lead you already know by id. To update many leads at once, use PUT /leads/mass-update.

Parameters. id (path) is the lead to update.

Request body. A JSON object with the fields to change. Any subset is accepted, for example first_name, phone, address fields, email, call_after, and a customFields object of your own field name and value pairs. Changing phone re-processes the number and clears the do-not-call flag on the lead.

Returns. 204 No Content on success. If part of the update could not be applied, 200 OK is returned with a messages array explaining what was skipped, for example a timezone_id that does not match the lead's country.

Example. PUT /api/leads/1 with body { "first_name": "John", "call_after": "2026-01-01 09:00:00" }