Collider is an open source library for continuous 2D collision detection, for use with game developement. Continuous collision detection basically means that the time and location of the collision are determined very precisely, as opposed to using a more traditional time-stepping and polling method. It was originally a Java project (which I had used in the game Weaponless), but has since been ported to Rust, and now the Rust version is the primary version.
Old Java project:
Collider is licensed under the Apache 2.0 License.