MetoolzyYAML / JSON Converter
Bidirectional
YAML to JSON and JSON to YAML.
Validation
Syntax validation with error messages.
Copy Result
One-click copy to clipboard.
Client-side
All processing in your browser. No data uploaded.
About YAML / JSON Converter
The YAML to JSON Converter (and JSON to YAML Converter) lets you switch instantly between two of the most widely used data serialization formats. YAML is prized for human readability and is the standard format for configuration files in tools like Docker Compose, Kubernetes, GitHub Actions, and Ansible. JSON is the universal language of APIs and web services. Converting between them is a daily task for developers, DevOps engineers, and data engineers. Paste YAML and get properly formatted JSON with correct indentation in one click. Or paste a JSON API response and transform it into clean YAML for use in a configuration file. The converter uses the js-yaml library, which provides full YAML 1.2 support including multi-line strings, anchors, aliases, comments handling, and complex nested structures. Both directions include syntax validation: if your input contains errors, you get a clear error message explaining what went wrong and where, saving you from hunting through large files for a missing colon or misaligned indentation. You can copy the result to clipboard or download it as a file. All processing happens in your browser with no data uploaded, making it safe for sensitive configuration data like API keys, database credentials, and infrastructure definitions.
How to Use YAML / JSON Converter
- Choose your conversion direction using the toggle at the top: "YAML to JSON" or "JSON to YAML".
- Paste your YAML or JSON into the left input panel.
- The converted result appears in the right panel automatically as you type.
- If there is a syntax error in your input, an error message will appear below the panels with details.
- Click "Copy" to copy the output to your clipboard, or click "Download" to save it as a .json or .yaml file.
- Switch directions at any time using the toggle — the panels will clear so you can start fresh.
Frequently Asked Questions
Does this support all YAML features?
The converter uses the js-yaml library which supports YAML 1.2, including nested mappings, sequences, multi-line strings (block scalars), boolean and number types, and null values. YAML anchors and aliases are resolved during parsing. Comments in YAML are ignored when converting to JSON since JSON has no comment syntax.
Why does my YAML boolean "yes" become true in JSON?
YAML 1.1 treated values like "yes", "no", "on", "off" as booleans. The js-yaml library used here follows the YAML 1.2 spec, where only "true" and "false" are booleans. If you paste older YAML that uses "yes"/"no", they will be converted to boolean true/false in the JSON output.
Can I convert Kubernetes or Docker Compose YAML files?
Yes. Kubernetes manifests and Docker Compose files are standard YAML. Paste the content directly and the tool will parse them correctly. Note that multi-document YAML files (separated by ---) will only parse the first document.
Why does JSON to YAML add extra quotes around some strings?
YAML requires quoting strings that could be ambiguous — for example, strings that look like numbers, booleans, or contain special characters like colons. The quotes ensure the value is always interpreted as a string.
Is there a file size limit?
There is no enforced size limit; the tool runs in your browser and is limited only by available memory. For very large files (hundreds of kilobytes), performance may slow down.
Is my data sent to a server?
No. All parsing and formatting is done client-side using JavaScript. Nothing is transmitted over the network.
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