Ferritin — Rust documentation MCP server

🩸 Ferritin

[![ci][ci-badge]][ci] [![crates.io version badge][version-badge]][crate]

[ci]: https://github.com/jbr/ferritin/actions?query=workflow%3ACI [ci-badge]: https://github.com/jbr/ferritin/workflows/CI/badge.svg [version-badge]: https://img.shields.io/crates/v/ferritin.svg?style=flat-square [crate]: https://crates.io/crates/ferritin

A terminal-based Rust documentation viewer

Ferritin reads rustdoc JSON output to display Rust documentation directly in your terminal. It supports local workspace crates, standard library documentation, and crates from crates.io, with search functionality and modern terminal features including mouse support, syntax highlighting, and clickable links.

Features

• Interactive documentation browser with keyboard and mouse navigation
• One-shot CLI for quick documentation lookups in the terminal
• Search across crates or within specific crates
• Works seamlessly across three contexts:
• Local workspace crates (requires nightly toolchain)
• Standard library (requires rust-docs-json rustup component)
• Crates from crates.io (fetched from docs.rs on demand)
• Modern terminal UI with features like italics, unicode box drawing, syntax highlighting, OSC8 hyperlinks, cursor changes in terminals that support it, and mouse hover previews
• Fast navigation with history and breadcrumb trail

Installation

Prebuilt binary (recommended)

Prebuilt binaries skip compilation and are available for x8664/aarch64 macOS, x8664 Linux, and x86_64 Windows.

If you have cargo-binstall, it reads the release metadata and installs the right binary for your platform:

cargo binstall ferritin

Otherwise, the installer scripts detect your platform, download the matching binary, and place it in ~/.cargo/bin:

macOS and Linux:

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/jbr/ferritin/releases/download/ferritin-latest/ferritin-installer.sh | sh

Windows (PowerShell):

powershell -c "irm https://github.com/jbr/ferritin/releases/download/ferritin-latest/ferritin-installer.ps1 | iex"

Both of the above always install the most recent release. You can also pick a specific version or download archives directly from the [releases page].

[releases page]: https://github.com/jbr/ferritin/releases

From source

To build from source (or for a platform without a prebuilt binary):

cargo install ferritin

Optional: Standard library documentation

To view documentation for std, core, and alloc:

rustup component add rust-docs-json

For local workspace documentation

Local crate documentation requires a nightly toolchain:

rustup toolchain install nightly

Note: There is a relationship between ferritin's version and the nightly toolchain version. Ferritin supports a range of recent rustdoc JSON format versions, and if your nightly generates a newer format, ferritin will make a best effort at parsing it.

Usage

Interactive mode

Launch the interactive browser:

ferritin -i

Once running, use h or ? to see available keybindings. Basic navigation:

• g - go to an item by path (e.g., std::vec::Vec)
• s - search (Tab to toggle between current crate and all crates)
• l - list available crates
• Arrow keys, j/k, or mouse to navigate
• Click on links to follow them

CLI mode

View documentation for a specific item:

ferritin get std::vec::Vec
ferritin get serde::Serialize

Search for items:

ferritin search "hash map"
ferritin search --crate tokio "spawn"

List available crates in your workspace:

ferritin list

Output format

Shortened. The full README is on GitHub.