The crates.io package index contains the necessary metadata for cargo to download crates and resolve their dependencies.
The package index is available at:
- https://index.crates.io/ as an HTTP API (sparse protocol)
- https://github.com/rust-lang/crates.io-index as a git repository
The index format is described in detail in The Cargo Book.
The crates.io index is maintained by the crates.io team.