If-None-Match

What is the If-None-Match header?

The If-None-Match request header is used mainly for conditional GET requests. The server will send the full resource only if the current ETag on the server does not match the client’s ETag.

API Usage & Best Practices

• Enable HTTP/CDN Caching: Essential for optimizing mobile apps or web frontends querying configuration, catalogs, or large asset datasets.
• Returns 304: If the ETags match on a GET or HEAD, return 304 Not Modified with no body. For any other method a failed condition is 412 Precondition Failed, which is how If-None-Match: * on a PUT stops a client from overwriting a resource it believes does not exist yet.

Examples

GET /v1/leads/lead_123 HTTP/1.1
If-None-Match: W/"3a84e27f01"