Online JSON Formatter, Validator & Converter

io9.me JSON Tools is a free, browser-based JSON formatter and validator. Paste raw JSON or upload a .json file to instantly format, validate, minify, or convert your data. All processing happens locally in your browser — nothing is sent to a server.

Features

• Format and beautify JSON with 2-space or 4-space indentation
• Validate JSON syntax with detailed error messages and line numbers
• Minify JSON by stripping whitespace for smaller payloads
• Convert JSON to YAML with a single click
• Compare two JSON documents side-by-side with structural diff highlighting
• Collapse and expand nested objects and arrays
• Upload .json files via drag-and-drop or file picker
• Download formatted or minified output
• Undo history to revert changes
• Keyboard-friendly Monaco editor with syntax highlighting

How to use

1. Paste your JSON into the editor, or click Upload to load a file.
2. Click Format to beautify, Validate to check syntax, Minify to compress, or To YAML to convert.
3. Use Compare mode to diff two JSON documents side-by-side.
4. Copy or download the result.

Common use cases

Pretty-print API responses, validate configuration files, minify JSON before embedding in code, convert JSON to YAML for Kubernetes manifests or CI/CD pipelines, and compare JSON payloads to find differences.

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