YAML Formatter, Validator & Converter

Format, validate, auto-fix, and convert YAML — supports anchors, aliases, multi-document streams

Input YAML

FormattedValid

name: DevBench
version: 1.0.0
description: Free online developer tools
features:
  - name: JSON Tools
    workspace: /json
  - name: YAML Formatter
    workspace: /yaml
settings:
  theme: dark
  analytics: true
  maxTools: 100
database:
  host: localhost
  port: 5432
  credentials:
    user: admin
    password: secret
replica:
  user: admin
  password: secret
  host: replica.db.local

The DevBench YAML workspace lets you format, validate, lint, and convert YAML entirely in your browser — nothing is sent to a server. Paste messy YAML and the formatter re-indents it with consistent 2-space indentation, normalises line endings, and collapses excess blank lines. The validator reports syntax errors with exact line and column numbers, and the linter flags common issues such as tabs, trailing whitespace, lines over 120 characters, and duplicate keys.

Features

Format — pretty-print YAML with 2-space indentation and clean blank lines

Validate & Lint — syntax errors, tab usage, long lines, duplicate keys with line numbers

Auto-Fix — one click removes tabs, trailing whitespace, and CRLF endings

YAML → JSON — convert any YAML document to formatted JSON

JSON → YAML — convert JSON back to clean YAML

Multi-document — handles --- separated YAML streams

What is YAML?

YAML (YAML Ain't Markup Language) is a human-readable data serialisation format widely used for configuration files — Kubernetes manifests, Docker Compose, GitHub Actions, Ansible playbooks, and countless CI/CD pipelines. Unlike JSON, YAML allows comments, multiline strings, anchors (&), and aliases (*) for reuse. Indentation (spaces only — never tabs) defines structure, making the format clean to read but easy to break if edited carelessly.

YAML vs JSON

YAML is a superset of JSON — valid JSON is also valid YAML 1.2

YAML supports comments (# comment); JSON does not

YAML uses indentation for structure; JSON uses braces and brackets

YAML anchors allow values to be reused without repetition

JSON is generally safer for machine-to-machine communication; YAML excels in human-edited config files