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Boost C++ Libraries
The Boost project provides free peer-reviewed portable C++ source libraries.
We emphasize libraries that work well with the C++ Standard Library. Boost libraries are intended to be widely useful, and usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use and does not require attribution for binary use.
The project website is www.boost.org, where you can obtain more information and download the current release.