Content-Length

What is the Content-Length header?

The Content-Length header indicates the size of the payload body in decimal number of octets (bytes) sent to the recipient.

API Usage & Best Practices

• Validate request sizing: Gateways check this header to immediately reject payloads exceeding limits with a 413 Content Too Large.
• Reject missing lengths only if you must: RFC 9112 lets a server answer a request that has a body but no Content-Length with 411 Length Required, but every HTTP/1.1 recipient must be able to parse chunked bodies, so reserve 411 for a server that genuinely cannot accept a body of unknown length, such as one that has to enforce a size limit before reading. An explicit Content-Length: 0 is a valid, empty body rather than a missing header, and shouldn’t trigger 411.

Examples

POST /v1/leads HTTP/1.1
Content-Type: application/json
Content-Length: 124