YAML Formatter

Validate and format YAML, and convert YAML to JSON or JSON to YAML — with clear error lines.

Sort keys

Open file

YAML input

Valid YAML

YAML output

# utilitech sample — docker compose
services:
  web:
    image: node:22-alpine
    ports: [ "3000:3000" ]
    environment:
      NODE_ENV: production
      TZ: Asia/Bangkok
    depends_on: [ db ]
  db:
    image: postgres:17
    volumes:
      - db-data:/var/lib/postgresql/data # keep data between restarts
volumes:
  db-data: {}

16 lines · 333 bytes

How to use

Format YAML checks your YAML and re-indents it consistently. Comments are kept (unless you sort keys).
YAML → JSON and JSON → YAML convert between the two — handy for Kubernetes manifests, Docker Compose, GitHub Actions and OpenAPI files.
Files with several documents separated by --- are supported.

Common YAML mistakes

Tabs aren't allowed for indentation — use spaces.
Values like yes, no, on or 08 may not mean what you expect; put them in quotes to keep them as text.
A colon followed by a space inside a value needs quotes: title: "Note: read me".
Everything runs in your browser — nothing is uploaded.