facet is a reflection library for Rust. One derive macro gives you serialization, pretty-printing, diffing, and more.

#[derive(Facet)]
struct Config {
    name: String,
    port: u16,
    #[facet(sensitive)]
    api_key: String,
}

From this single derive, you get:

• Serialization — JSON, YAML, TOML, MessagePack
• Pretty-printing — Colored output with sensitive field redaction
• Diffing — Structural comparison between values
• Introspection — Query type information at runtime

Choose your path

Guide

Use facet in your app

Install a format crate, derive Facet, configure attributes, and ship with great diagnostics.

Ecosystem

See the whole map

Every facet-related crate — formats, schema codegen, CLI, diffing, pretty-printing — with links to docs and source.

Showcases

See it in action

Interactive examples for JSON, YAML, args parsing, pretty-printing, diffing, and more.

Reference

Look it up fast

Attributes catalog and format matrix.

Extend

Build on reflection

Create extension attributes, read data with Peek, build values with Partial, and architect new format crates.

Contribute

Work on facet itself

Architecture, derive internals, vtables, unsafe invariants, and the contributor workflow.

Quick links

• Getting Started — Install, derive, ship
• Ecosystem map — Every facet crate and where to find it
• JSON guide — The flagship workflow
• Format Support Matrix — Feature comparison across format crates
• GitHub · crates.io · docs.rs · Discord