Response Codes | HubLinks | API Documentation

All API responses return a standard HTTP status code. Every body includes a success flag; on error it is false and a message field explains what went wrong.

{
	"success": false,
	"message": "Campaign not found: CAMPXXXXXXXXXXXXXXXXXXXX"
}

A request that fails never returns 200, so you can rely on the status code alone.

Status Codes

Code	Status	Description
200	Success	Request was successful.
400	Bad Request	A parameter or the request body is invalid (a malformed `limit` or `last_key`, a body that is not valid JSON, a field that cannot be set), or the campaign is not ready, e.g. it has no filters or seats yet.
401	Unauthorized	The `X-API-KEY` header is missing.
403	Forbidden	The API key is invalid, or it has no access to this account, endpoint or method.
404	Not Found	The route does not exist, or the resource (campaign, prospect, seat, sender, template, thread, message…) does not exist in this account.
429	Too Many Requests	Rate limit exceeded. Back off and retry.
500	Internal Server Error	An unexpected error occurred on the server.

Request bodies

Send only the fields listed on each endpoint. Any other field returns 400, except when adding a prospect, where unknown fields are ignored.

Rate limits

Every API key, account or agency, has the same limits:

Sustained rate	Burst	Daily quota
10 requests/s	20 requests	250,000 requests

Requests over the limit return 429. Retry with exponential backoff, starting at about one second.