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, KDL, 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.

Reference

Look it up fast

Attributes catalog, format matrix, extension namespaces, and FAQs in one place.

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

• Format Support Matrix — Feature comparison across format crates
• Extension Attributes — Format-specific attribute namespaces
• GitHub — Source code and issues
• docs.rs — API documentation