Klarna imposes certain limits on API requests to ensure the stability and reliability of our services.

Requests sent to the API should not include any headers that are not strictly necessary and specified by the API, except the standard HTTP headers such as:

• Content-Length
• Content-Type
• Host
• Authorization
• User-Agent

Especially some observability platforms are by default including some potentially very large header used for tracing between internal systems also when making external calls. Such headers shall not be included when making calls to Klarna APIs. We are sanitising the request from a few common trace-agents.

Any request must adhere to the following limits:

• Any individual header including header key + value: 6KB
• Total amount of space allowed for all header keys + values: 20KB

The default maximum request body size in our API is 1MB. Any request with a body size exceeding this limit will not be processed and will return an error code 413 (Payload Too Large). Some API endpoints may exceed this limit and will state this in their documentation.