Free JSON Formatter & Validator
Format, validate, and minify JSON online. Beautify JSON with custom indentation, check for errors, and download results. 100% free, no signup required.
JSON (JavaScript Object Notation) is a lightweight data interchange format that's easy for humans to read and write, and easy for machines to parse and generate. It's based on a subset of JavaScript and is the most popular format for transmitting data in web applications.
JSON is used extensively in REST APIs, configuration files, and data storage. This free online JSON formatter helps developers quickly format, validate, and minify JSON data without installing any software.
Common JSON Use Cases:
- API request and response payloads
- Configuration files (package.json, tsconfig.json)
- Data exchange between client and server
- NoSQL database storage (MongoDB, CouchDB)
- Log files and structured data
Paste unformatted JSON into the editor on the left, or click "Upload JSON" to load local .json files directly into your browser.
Choose 2 spaces for standard compact web projects, 4 spaces for extended readability, or tab indentation depending on team style guidelines.
Click "Validate JSON". The parser highlights syntax errors, unescaped quotes, trailing commas, or missing brackets with line numbers.
One-click copy formatted JSON to your clipboard, minify to reduce payload size over HTTP networks, or download as a clean .json file.
Is my JSON data stored or sent to any server?
No. All parsing, validation, minification, and formatting happen 100% locally in your client browser via the native JavaScript V8 engine. Zero payload data is ever logged or transmitted across the network.
Why does JSON.parse() throw "Unexpected token in JSON at position..."?
Common culprits include trailing commas after the last array item or object key (valid in JavaScript, illegal in strict RFC 8259 JSON), single quotes instead of double quotes, and unquoted keys.
When should I minify JSON vs format it?
Format JSON when reviewing API responses, writing documentation, or debugging locally. Minify JSON for production API endpoints, caching layers, and database records to save bandwidth and reduce transmission latency.
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