saneyaml

Serde-first YAML for Rust — load config straight into your structs with #[derive(Deserialize)], with real YAML 1.2 semantics (so NO stays the string "NO", not false), useful diagnostics, and resource limits built in. Pure Rust, #![forbid(unsafe_code)].

Static overview graphic. See source notes and benchmark caveats.

Install

[dependencies]
saneyaml = "0.3.0"

Then use it:

use serde::{Deserialize, Serialize};

#[derive(Deserialize, Serialize)]
struct Config {
    name: String,
    port: u16,
}

fn main() -> Result<(), saneyaml::Error> {
    let cfg: Config = saneyaml::from_str("name: web\nport: 8080\n")?;
    assert_eq!(cfg.port, 8080);

    let text = saneyaml::to_string(&cfg)?;
    println!("{text}");
    Ok(())
}

Coming from the archived serde_yaml? It's close to a drop-in — see MIGRATION.md.

Why saneyaml

Most Rust YAML libraries make you pick one or the other: serde_yaml's ergonomics (now archived, and YAML 1.1-flavored), or a maintained YAML 1.2 parser like yaml-rust2 or saphyr that hands you a node tree to walk by hand. saneyaml is serde-first and YAML 1.2-correct.

• Serde-first — from_str / from_slice / from_reader, to_string / to_writer, and a serde_yaml-style Value. Deserialize straight into your config structs — no hand-walking a node tree.
• YAML 1.2 by default — correct scalar resolution, no "Norway problem": NO/on/off/yes stay strings. Opt into YAML 1.1 / serde_yaml-style resolution explicitly via schema modes (Core, Json, Failsafe, LegacySerdeYaml).
• Diagnostics — line/column, in-document key path (e.g. server.port), and opt-in source-caret rendering.
• Safe on hostile input — unsafe-free, with structural resource limits: input-size, alias-expansion, nesting-depth, scalar-length, and collection-size controls. Reader-backed entrypoints fully buffer bounded input, and these limits are not wall-clock or resident-memory guarantees.
• Streaming and source-preserving edits — pull-based event/document iterators that bound retained parsed documents while source bytes remain buffered, plus edit(...) for path-based config refactors that keep comments, anchors, ordering, and untouched bytes.
• Benchmarked — real-world config corpus runs are tracked against serde_yaml, yaml-rust2, and saphyr; see BENCHMARKS.md.

Status

Pre-1.0 (0.3.0), MSRV Rust 1.88, and actively maintained. The public API is a preview surface but is treated as SemVer-visible: breaking changes and MSRV bumps are explicit, documented release decisions. The road to 1.0 is about locking the surface down, not expanding it — stability is the goal.

Documentation

Start with the Guide, or read the same files in-repo: Getting started and the Cookbook. The docs index maps everything else.

• Guides — Getting started · Cookbook · Schema modes · Diagnostics · Untrusted input · Editing files · Streaming
• Migrating — from serde_yaml
• Reference — Compatibility · Architecture · Benchmarks · API docs
• Project — Security · Contributing · Changelog

License

MIT — see LICENSE.md.