About YAML Formatter & Validator
The YAML formatter checks a document against the YAML 1.2 Core schema, re-indents it, and can convert between YAML and JSON. Errors include a line and column when the parser provides them. Nothing is sent off your device, and custom tags are not turned into objects or code.
How to use YAML Formatter & Validator
- Paste YAML, or JSON if you are converting to YAML.
- Choose Format, YAML to JSON, or JSON to YAML, and an indent of 2 or 4 spaces.
- Select Format. A syntax error shows the line and column when the parser knows them.
- Copy the result or download it.
Examples
A config file
Re-indent a mapping with nested lists so the structure is easy to review.
YAML to JSON
Convert a single document to JSON. Several YAML documents become a JSON array.
Limitations
- Only the YAML 1.2 Core schema is supported. Custom tags are rejected rather than executed.
- Aliases are expanded only up to a fixed cap, so a document cannot grow without bound.
- Formatting keeps anchors when you stay in YAML. Converting to JSON resolves them and drops comments.
Privacy
This tool processes everything locally in your browser tab. Your input is not uploaded to Utilhex or any third party, and it is discarded when you close or reload the page. Read the privacy policy for details.
Frequently asked questions
Is my input sent anywhere?
No. Processing happens in your browser. Utilhex does not send tool input to its servers, analytics, or any AI service.
Will formatting change numbers or strings?
The parser keeps YAML types such as strings, numbers, booleans, and null, then writes them back. Quoted strings stay strings. Comments are kept in YAML output and dropped when converting to JSON.
Are multiple documents supported?
Yes for formatting. YAML to JSON turns them into one JSON array and says so.