curl

A free command-line tool for fetching web addresses, used by programmers and in countless scripts. A visit from it is a person's program rather than a browser: a developer checking the site, a script, or a scanner.

Worth knowing: curl was started in 1998 by Daniel Stenberg in Sweden, who still leads it, and it is built into cars, TVs, phones and games consoles: its makers estimate it is installed over twenty billion times.

A sign of the times: in January 2026 Stenberg shut down curl's bug bounty, which paid people for finding security flaws, because it was flooded with fake reports written by AI. Over almost seven years it had found 87 real vulnerabilities and paid out over $100,000, but by 2025 fewer than one report in twenty turned out to be real.