Errors and limits

Limits

Limit	Value
Requests	300 per minute per API key, across all users. Over the limit answers `429`.
Contacts per request	10,000 (create and batch add).
Request body	50 MB.
Analytics range	366 days.
List name	150 characters. Group name 100.
Contact name	500 characters. Phone number 50. Up to 10 additional numbers.

Every error is JSON with an error string and, where useful, details. Validation errors list each problem:

{
  "error": "Invalid request",
  "details": [ { "path": "contacts.0.phoneNumber", "message": "phoneNumber is required" } ]
}

Status	Meaning
`400`	Malformed body or query, unknown field, missing user header, impossible date.
`401`	Missing or wrong API key.
`404`	User not found; list not found or not owned by the user; contact not in the list.
`429`	Rate limit exceeded.
`500`	Unexpected server error. Safe to retry once.
`502`	PowerDialer could not verify the user with its identity provider. Retry later.
`503`	The API is switched off on the server.

Batch writes are atomic: a 500 on a batch add leaves nothing half-applied, so retry the whole batch.