To keep the API available to all users, the system enforces request rate limiting. Requests that hit any of our rate limits will receive a 429 Too Many Requests response, which contains the standard Retry-After header indicating how many seconds the client should wait before retrying the request.

Here is an example of such error response:

HTTP/1.1 429 Too Many Requests
Content-Type: application/json
Retry-After: 0.825

{"status":429,"message":"Too many requests","retryAfter":825}

Limits are allocated per API key. Different endpoints may have different rates.

Rates for common endpoints:

/api/ - 3 reqs/sec, default rate for all
/api/message/next - 100 reqs/sec
/api/message/send - 100 reqs/sec
/api/proxy/send - 100 reqs/sec
/api/project/create - 10 reqs/hour
/api/contact/import - 10 reqs/hour

Quotas

Many resources in the system limited by quotas, system wide or account specific. Quotas marked with * can be changed by support on request for each account individually.

Min number of contacts for outsourced orders to be accepted, 2500. *
Max contacts that can be created via segmentation tool, 50000.
Max contacts that ca be downloaded directly, otherwise only via reports. 200000. *
Max contacts that can be download by via API or reports, 1000000. *
Max number of test messages allowed to send per project. 30. *