🔧 Faster and lightweight YAML v1.2 parser for JavaScript and TypeScript.

• Zero runtime dependencies
• Single-file hand-written recursive-descent parser
• Compatible with Node.js (18+), Bun, and Deno

Install

# Node.js
npm i yaml.min

# Bun
bun add yaml.min

# Deno
deno add npm:yaml.min

Usage

Import

ES Modules

import { parse } from 'yaml.min';

CommonJS

const { parse } = require('yaml.min');

Quickstart

import { parse } from 'yaml.min';

const data = parse(`
  server:
    host: localhost
    port: 8080
    tags: [web, production]

  database:
    enabled: true
    ports:
      - 8001
      - 8002
      - 8003
`);

data.server.host; // "localhost"
data.server.port; // 8080
data.server.tags; // ["web", "production"]
data.database.enabled; // true
data.database.ports; // [8001, 8002, 8003]

Supported Types

Strings

Plain, single-quoted, double-quoted, and all escape sequences:

plain: Hello, World!
single_quoted: 'no \escapes here'
double_quoted: "hello\nworld"

Escape sequences: \0, \a, \b, \t, \n, \v, \f, \r, \e, \\, \", \/, \N, \_, \L, \P, \xHH, \uHHHH, \UHHHHHHHH.

Block Scalars

Literal (|) and folded (>) block scalars with chomp indicators:

literal: |
  first line
  second line
  third line

folded: >
  This long text
  will be folded
  into a single line.

strip: |-
  no trailing newline

keep: |+
  trailing newlines
  are preserved

indent: |2
    explicit indent
    level

Integers

decimal: 42
positive: +99
negative: -17
hex: 0xDEADBEEF
octal: 0o755

Floats

pi: 3.14159
scientific: 6.626e-34
positive_inf: .inf
negative_inf: -.inf
not_a_number: .nan

Booleans

enabled: true
disabled: false

Also accepts True/False and TRUE/FALSE.

Null

tilde: ~
word: null
empty:

Also accepts Null and NULL.

Collections

Block Mappings

server:
  host: localhost
  port: 8080
  tls:
    enabled: true

Block Sequences

fruits:
  - apple
  - banana
  - cherry

Flow Collections

sequence: [1, 2, 3]
mapping: { name: Tom, age: 30 }
nested: { tags: [a, b, c] }

Anchors and Aliases

defaults: &defaults
  adapter: postgres
  host: localhost

development:
  database: dev_db
  <<: *defaults

production:
  database: prod_db
  <<: *defaults

Explicit Keys

complex key: value

Document Markers

---
first: document
...
---
second: document

TypeScript

The parse function accepts a generic type parameter:

import { parse } from 'yaml.min';

type Config = {
  database: {
    host: string;
    port: number;
  };
};

const config = parse<Config>(`
  database:
    host: localhost
    port: 5432
`);

config.database.host; // string
config.database.port; // number

Benchmark

Measured with hyperfine parsing the same YAML payload:

| Parser | Times slower than yaml.min | Package Size | | -------------------------------------------- | ------------------------------ | ------------------------------------------------------ | | ✨ yaml.min | 1.00x (baseline) | | | js-yaml | 2.05x ↓ | | | yaml | 19.82x ↓ | |

• Each benchmark parses the same YAML snapshot 5,000 times per run, with 10 measured runs and 5 warmup runs via hyperfine. See the benchmark directory for details.

Security Policy

Please check the SECURITY.md.

Contributing

See the Contributing Guide and please follow our Code of Conduct.

Acknowledgements

• 
• yaml.min is inspired by js-yaml, reimplemented as a hand-written recursive-descent parser for performance and zero dependencies.

License

yaml.min is under the MIT License. Copyright © 2026-present Weslley Araújo and yaml.min contributors.