Developer Tools
YAML Formatter
Beautify and validate YAML configuration files in your browser. Supports multi-document streams separated by `---`, optional 2- or 4-space indentation, and a validate-only mode that reports parse errors with the exact line and column. Nothing ever leaves your device.
Your input is processed locally in your browser. It is not uploaded to Dueneo.
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How to use
- 1
Paste your YAML
Drop raw YAML into the left-hand editor. Multi-document streams (separated by `---`) are supported — each document is parsed and re-emitted independently.
- 2
Pick indent size or validate-only
Choose 2 or 4 spaces for indentation. Toggle Validate only to skip formatting and just check that the YAML parses.
- 3
Format or validate
Click Format YAML (or Validate YAML). Parse errors include the line and column where the parser failed, plus a short excerpt.
- 4
Copy or download
Use Copy to put the result on your clipboard, or Save to download it as formatted.yaml.
Common use cases
- Tidy a hand-written docker-compose.yml or CI config before committing.
- Validate that a Kubernetes manifest has correct indentation before applying it.
- Normalise indentation across a team's YAML files (2 vs 4 spaces).
- Check a multi-document YAML stream (e.g. a Helm chart) parses correctly.
Limitations
- Inputs larger than 1 MB are rejected to keep the tab responsive.
- YAML aliases and anchors are resolved on dump (
noRefs: true) — the output is fully expanded. - The formatter uses
js-yaml's default schema, which supports the JSON, core and some extended types. Custom tags may not round-trip. - Line and column numbers come from
js-yaml's parser and may point one line beyond the actual issue when the error is at the end of the document.