Churro is a global, verified cache of precompiled Rust dependencies. Our builders compile popular crates.io crates once; Cargo downloads them instead of compiling them. It is free and open source, MIT or Apache-2.0.
A clean Rust build spends most of its time compiling dependencies that thousands of other projects compile too. Churro removes that work. It runs as Cargo's RUSTC_WRAPPER: when a dependency is in the cache with exactly your inputs (source, compiler, target, flags, features), Churro downloads the result instead of compiling it. When it isn't, rustc runs as usual, so the worst case is a normal build. Only your own code compiles.
We compile everything in the cache. Our builders run in sealed sandboxes with no network, and a crate is published only when two independent builders produce byte-identical output. Each result is signed. Nothing is uploaded from your machine, and the client has no way to publish. Churro checks every signature and hash on your machine before it uses a result, so the server is only storage.
Anyone who builds Rust from scratch often: CI runners, fresh clones, git worktrees and Docker builds. Teams that want the same thing for private code can run their own cache with the same client and their own builders and keys.
Churro is open source at github.com/usechurro/churro, under the MIT or Apache-2.0 license. It is early software: the client and the cache are pre-release, and the catalog shows exactly which crates have been built so far.