Cratesio

crates.io is the official package registry for the Rust programming language. It hosts crates, which are reusable Rust libraries or binaries, and serves as the primary source for dependency resolution in the Rust ecosystem. Crates.io works with Cargo, Rust's package manager, to publish crates, resolve dependencies, and download crate files during builds. Developers publish crates to crates.io, assign semantic versions, and provide optional metadata such as a description, homepage, repository link, and documentation URL. Each crate can have multiple versions; maintainers can yank a version to prevent downloads while leaving other versions available.

The registry uses a two-tier architecture. A registry index, stored in a Git repository, allows Cargo to discover crates and their versions efficiently. The actual crate archives (the crate tarballs) are stored and served by crates.io. The platform exposes an HTTP API that allows programmatic access to crate metadata, version lists, dependencies, and search results, and supports user authentication via API tokens. Public crates are publicly searchable and downloadable; private crates can be restricted to authorized users or teams.

Crates.io is operated as part of the Rust project ecosystem and is maintained by the Rust community. It aims to provide a stable, searchable, and secure registry for Rust libraries and applications, enabling widespread sharing and reproducible builds through Cargo's dependency resolution.