HTTP headers / request header
Accept-Language: tr-TR, tr;q=0.9, en;q=0.8
Expresses the user's preferred languages for content negotiation. Localized APIs and websites use it to pick a translation.
Geo-IP often overrides it in practice; for APIs an explicit ?lang= parameter is usually more predictable.
The fastest way to see what Accept-Language 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 · If-None-Match · If-Match · If-Modified-Since
Build the request, send it, read raw headers and timing — from your iPhone. Free to start.