It's a dependency injection crate that focuses on simplicity of use. It relies on a procedural macro to do a lot of the busy work, and also provides a declarative macro to help initialize containers. Resolving dependencies also relies on async (in order to handle cases like establishing a DB connection, which might rely on async). Both procedural macros and async support can be turned off through features to help with compile times and to just turn off what you're not using.
I plan on getting this crate to 1.0 and maintain it for a long time (that was my current issue with existing DI crates, they seemed not feature-complete and not-maintained), so please file issues on any documentation or crate issues, even for minor things like typos. I'll gladly take any feedback on API design as well. If you feel the crate should have something that it doesn't, please file an issue for that as well!