YAML File Tools

Free online YAML tools

Format, validate and edit your YAML

Find syntax errors, inspect anchors and aliases, and make changes with a source editor or simple forms. Open your file to get started.

1. Open your YAML

Local processing · .yaml or .yml · up to 25 MiB per input. Conversion and comparison have additional safety limits.

Paste YAML
  1. Format and validateUse Format and Validate; fix errors in Source.
  2. Download your YAMLSave the edited file from the editor.
service:
  name: harbour-api
  enabled: true

See YAML-specific structure

The summary reports documents, anchors, aliases and custom tags instead of treating YAML as relaxed JSON.

Format and validate

Duplicate keys and invalid syntax produce clear errors. Alias expansion is limited to protect the browser from unusually complex input.

Your YAML stays local

File and pasted contents are processed locally. Ordinary page and asset requests still reach the hosting provider.

How to format and validate a YAML file

  1. Open a .yaml or .yml file, paste YAML, or choose the sample above.
  2. Review Formatted YAML and the inspector. Fix syntax errors and duplicate keys in Source.
  3. Download your YAML after checking the result.

Need to change configuration values? Edit YAML files online with Source or the Easy editor.

Frequently asked questions

Can AI help with a selected YAML value?

When configured, open Assistance, select literal source and explicitly include its preview. Review the generated source changes and local syntax/schema validation before applying one undoable edit. Comments and unselected source remain intact; the model is shown and applying does not save the file. Unconfigured assistance stays unavailable.

How do I format and validate YAML online?

Choose a .yaml or .yml file, paste YAML, or try the sample. In the editor, use Formatted YAML to review formatting and syntax errors. Fix invalid syntax or duplicate keys in Source, then download the YAML file.

What YAML structure can I inspect?

The inspector reports documents, anchors, aliases and custom tags. Alias expansion is limited to protect your browser from unusually complex input.

Does my YAML file get uploaded?

Local editing parses YAML in your browser. Optional Assistance sends only your goal and source text you explicitly select and include to the displayed processing destination. The browser uses OpenRouter and its configured model provider; installed desktop versions offering a local option can use your configured Ollama service instead. Ordinary page and asset requests also reach the hosting provider.

Can every YAML file become JSON?

No. Whole-file JSON export is unavailable for multiple documents. Explicit tags, non-string or complex keys, exact numbers and excessive alias expansion can also require YAML source. Read-only Query document selects one document explicitly and only accepts its safe JSON representation.