I would also like to nominate dprint, a super fast code formatter which I've been using for my recent projects. It formats Markdown, TypeScript, JavaScript, JSON, TOML and many other types natively via Wasm plugins.
It also formats Rust code by calling out to rustfmt — and it even formats Rust code embedded into Markdown files. Oh, and @dsherret has been extremely helpful whenever I filed a bug report or feature request!