curl 8.21.0

curl transfers data with URLs. That sentence undersells it: curl and its library libcurl are installed on billions of devices and are, by a wide margin, the most widely deployed piece of networking software most people have never thought about.

The commands worth knowing

# Follow redirects, save with the remote filename
curl -LO https://example.com/file.tar.gz

# Show only the response headers
curl -I https://example.com

# POST JSON to an API
curl -X POST https://api.example.com/items \
  -H 'Content-Type: application/json' \
  -d '{"name":"test"}'

# Fail loudly on HTTP errors instead of saving the error page
curl -fsSL https://example.com/script.sh

# Time the request phases
curl -w '%{time_namelookup} %{time_connect} %{time_total}\n' -o /dev/null -s https://example.com

That -fsSL combination is worth memorizing. -f fails on HTTP errors, -sS silences the progress meter while keeping errors visible, and -L follows redirects. It is the difference between a script that stops on failure and one that cheerfully writes a 404 page to disk.

curl or wget

Both download files and the overlap is large. The practical split:

• wget is better at recursive downloads and mirroring a site
• curl is better at everything involving APIs, custom methods, headers, and authentication

curl also exists as a library, which is why it ends up embedded in so much other software.

Our curl and wget comparison covers the distinction in more depth.

Security posture

curl has an unusually good security process for a project of its age and reach, with a published advisory database, a bug bounty, and a maintainer who writes candidly about the tradeoffs. It also gets a steady stream of CVEs, because software this widely deployed and this protocol-heavy attracts attention.

Keep it current. It is a dependency of an enormous amount of other software, and the version your distribution ships is usually patched even when the version number looks old.

Verify Your Download

Source releases are signed with GPG, with checksums and signatures on the download page.