Sendwire

The developer's HTTP client. It sends the request and shows you the DNS lookup, the TCP connect, the TLS handshake, the certificate chain and every byte in both directions.

These pages describe what it does and how. If you are looking for the shortest possible start, send your first request; if you are here because a request is behaving oddly, reading the exchange is the page that matters.

What is here

Install	macOS, Windows, Linux. No account.
Your first request	Sixty seconds, end to end.
Reading the exchange	The tab the rest of the app is built around.
Capture proxy · Inbound · HAR files	Watch real traffic — or receive it — then replay it.
Scripting · script reference	Real JavaScript, not a template language.
Suites · Load testing	Chain requests, then put them under load.
Command line	The same runs, in CI.
Privacy and data	What leaves your machine, and what doesn't.

Where your data lives

In a JSON file on your disk, at a path the app will tell you — bottom left of the window, and sendwire where on the command line. It is saved as you type.

There is no account, no sync and no cloud. The only things that leave your machine are the requests you send, a version check when the app starts, and anonymous, scrubbed crash & usage reports — on by default, disclosed on first run, and one click to turn off. No request data or personal info is ever included. The full account is on Privacy and data.