How do I get started using libtorrent in a C++ project?

Start with the official tutorial, which the project describes as an introduction to using libtorrent in C++. From there, use the reference documentation for API details, follow the site's download and building pages to get the library compiled, and study the bundled simple BitTorrent client as a working example of the library in use. libtorrent is a feature-complete C++ BitTorrent implementation focused on CPU efficiency, memory efficiency, and ease of use, and it runs on embedded devices as well as desktops.

A practical starting sequence

1. Read the tutorial first

The tutorial is the intended entry point for C++ users. It introduces how the library is used before you dive into the full API surface. Read it end to end once; it gives you the vocabulary (sessions, torrent handles, alerts) you will need when reading the reference.

2. Get and build the library

The site provides dedicated download and building pages. Use them rather than guessing at build steps, since libtorrent is a C++ library you compile and link into your own project. The building page is the authoritative source for prerequisites and build options.

3. Keep the reference documentation open

The reference documentation is where you look up exact class and function behavior. Use it as a lookup resource while writing code, not as a first read.

4. Study the bundled example client

libtorrent ships with a simple BitTorrent client that demonstrates use of the library. Reading its source is the fastest way to see how the pieces fit together in a real program. Compare what it does against the tutorial as you go.

What to expect from the library

The project also states it is a feature-complete BitTorrent protocol implementation, so you are not assembling partial protocol support yourself.

Licensing before you commit

libtorrent is released under the BSD license. You can use the library in your project without releasing your source code. The one requirement stated is that you credit the author by including the libtorrent license in your software or documentation. Contributing features back is appreciated but not required; patches can go to the mailing list or the bug tracker.

Where to get help

• Mailing list — the stated place for general libtorrent discussion and questions.
• Bug tracker / GitHub — for reporting bugs; the project is hosted on GitHub.
• IRC — the maintainer is usually reachable as hydri in #libtorrent on irc.freenode.net, per the site.

Common sticking points

• Skipping the tutorial and going straight to the reference. The reference documents the API but does not teach the flow; the tutorial does.
• Ignoring the example client. It is the clearest demonstration of library usage the project provides, so treat it as required reading rather than optional.
• Forgetting the license notice. BSD still requires the license text in your software or documentation, even though your source can stay closed.
• Version drift. The site lists upgrade guides for 2.1, 2.0, and 1.2, so check which version you are building against and read the matching upgrade notes if you follow older examples.

If you are evaluating whether libtorrent fits your project at all, the introduction and features pages give the project's own summary of scope and goals before you invest time in the tutorial.