How do I validate JSON online?

Paste your JSON into the input panel. The formatter instantly checks syntax and highlights errors with line numbers. Invalid JSON is flagged before any formatting occurs.

Can I minify JSON to reduce file size?

Yes. Toggle the 'Minify' option to strip all whitespace and produce the most compact valid JSON. Useful for reducing API payload size and config files.

Does this tool support large JSON files?

The formatter handles files up to several megabytes in the browser. For very large files (50 MB+), consider splitting them first since all processing happens in your device's memory.

What indentation styles are available?

You can choose 2 spaces, 4 spaces, or tabs. The default is 2 spaces, which matches most JavaScript/TypeScript project conventions.

Is my JSON data sent to a server?

Never. The formatter runs entirely in your browser using JavaScript. Your JSON stays on your device, making it safe for API keys, tokens, and sensitive configuration.

Can I format JSON from an API response?

Absolutely. Copy the raw JSON response from your browser DevTools, cURL, or Postman and paste it in. The tool instantly formats it with proper indentation and syntax colours.

How is this different from browser DevTools?

This formatter offers one-click minification, validation error messages, configurable indent size, and a copy button — all in a distraction-free interface without needing to open DevTools.

Does it handle JSON with comments (JSONC)?

Standard JSON does not allow comments. If your input has comments, the validator will flag them as syntax errors. Strip comments first or use a YAML formatter for commented configs.

JSON Formatter

Format Live

Format, validate, minify and explore JSON with syntax highlighting.

About this tool

JSON Formatter — Format, validate, minify and explore JSON with syntax highlighting. Free, fast and private. Runs entirely in your browser at Quick Calci Tool

Examples

Common scenarios for the JSON Formatter.

Pretty-print API response

Indent a one-line JSON payload from cURL.

json: {"id":1,"name":"Ada","tags":["dev","math"]}

Indented multi-line JSON with 2-space tabs.

Spot a syntax error

Detect a trailing comma the API rejected.

json: {"a":1,"b":2,}

Error at column 13: unexpected token '}'

Who uses the JSON Formatter?

Common scenarios and audiences for this tool.

API developers

Debug REST and GraphQL responses by formatting raw JSON payloads into readable, indented structures.

DevOps engineers

Validate and format JSON configuration files (package.json, tsconfig, Terraform state) before committing changes.

QA testers

Compare API response shapes by formatting both expected and actual JSON side-by-side for quick visual inspection.

Students learning web APIs

Understand nested data structures by expanding compact API responses into human-readable indented views.

Technical writers

Format JSON code samples for documentation with consistent indentation that renders cleanly in docs sites.

Frequently asked questions

Everything you need to know about the JSON Formatter.