YAML to JSON Converter

Choose multi-document handling

Use Multi-document policy when the input contains more than one document. Select one of these options:

• Auto (single value if 1 doc, array if more) outputs one value for one document and an array for multiple documents.
• Always output an array of documents always returns an array.
• Convert first document only ignores later documents.
• Error if more than one document stops when the input contains multiple documents.

Changing this control reprocesses non-empty input immediately.

Choose output formatting

Select Pretty (indented) for readable line breaks, or Compact (minified) for a single compact JSON value. With indented output, choose 2 spaces, 4 spaces, or Tab. Changing the output format or indent size updates an existing result.

Copy, download, or clear the result

• Use Copy JSON to copy a converted result. The button stays disabled until conversion succeeds.
• Use Download JSON to save the result as converted.json. It is also disabled until conversion succeeds.
• Use Clear to reset the current input and result.

Supported behavior and parser limitations

The implementation uses a self-contained YAML subset parser. The page does not provide a complete supported-syntax matrix, so do not assume that every YAML feature is accepted.

• It handles block and flow mappings and sequences, quoted and plain scalars, nulls, booleans, integers, and floats.
• Anchors and merge keys are expanded when used. An alias must refer to an anchor already available at that point in parsing; otherwise it produces a parse error.
• .inf, -.inf, and .nan become JavaScript non-finite values. When serialized with JSON, those values become null.
• Literal (|) and folded (>) block scalars are handled, but trailing blank lines and final newline behavior are not guaranteed to be preserved exactly.
• The tool converts YAML to JSON only. It does not edit or clean the original YAML, and it does not convert JSON back to YAML.

Troubleshooting conversion failures

• If the input is empty, the tool shows Paste or upload YAML content first.
• If a selected file cannot be read, it shows Could not read this file.
• If copying fails, it shows Could not copy to clipboard.
• YAML syntax and parser errors include a reported line and column. The multi-document error from Error if more than one document is a generic policy error without a source location.

Large-file preview behavior

If a selected file is longer than 200,000 characters, the textarea shows only the first 200,000 characters and adds a truncation notice. The full file remains in rawText and is processed. The implementation does not define a maximum accepted input size or a practical browser performance limit for very large content.

Privacy and processing

The conversion workflow does not upload the selected content: the browser FileReader reads it and the local parseYamlToDocuments parser processes it in your browser. The implementation does not document broader page network activity.

Frequently Asked Questions