HTTP headers / request header
User-Agent
User-Agent: ReqPad/1.1.2 (iPhone; iOS 19)
What it does
Identifies the client software making the request. Servers use it for logging, stats and occasionally (sigh) feature gating.
The gotcha
Some WAFs block requests with empty or "suspicious" User-Agents — if cURL works and your code does not, compare this header first.
Debugging headers on a phone
The fastest way to see what User-Agent 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-None-Match · If-Match
Inspect User-Agent on a live request.
Build the request, send it, read raw headers and timing — from your iPhone. Free to start.