HTTP headers / request header

If-None-Match

If-None-Match: "33a64df551425fcc"

What it does

Conditional GET: "give me the resource only if its ETag changed". Unchanged → 304 with empty body, saving bandwidth.

The gotcha

Your HTTP client may add it automatically from its cache — the reason you get mysterious 304s in debugging sessions.

Debugging headers on a phone

The fastest way to see what If-None-Match is actually doing is to send the request and read both sides raw — ReqPad shows auto-generated and custom headers for every request, on all six protocols, with history. Related references: status codes · Authorization · Accept · Accept-Encoding · Accept-Language · If-Match · If-Modified-Since

Inspect If-None-Match on a live request.

Build the request, send it, read raw headers and timing — from your iPhone. Free to start.

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