JSON Formatter & Validator Online
Format, beautify, and validate JSON instantly. 100% client-side — your data never leaves your browser. No signup, no tracking of your content.
Output will appear hereRuns entirely in your browser. Your JSON never touches a server.
Pinpoint syntax errors with exact line and column numbers.
Format with 2 spaces, 4 spaces, or tabs — whatever your team uses.
Why JSON formatting matters
JSON (JavaScript Object Notation) is the de-facto format for APIs, configuration files, and data interchange. When you receive a minified API response or work with a cramped config file, reading it is painful without proper indentation. JSON Mint beautifies JSON with consistent spacing so you can quickly spot structure, debug issues, and share readable snippets with teammates.
Unlike other online formatters, JSON Mint never sends your data to a server. Everything — parsing, validation, formatting — runs locally in your browser using the standard JSON.parse API. That means you can safely format sensitive payloads, internal API responses, and production configuration without privacy concerns. The tool works offline once loaded, and responds instantly — no network round-trip, no rate limits, no accounts.
Common use cases include debugging REST and GraphQL responses, cleaning up log output, validating configuration files before deployment, and preparing JSON examples for documentation. For each case, JSON Mint surfaces syntax errors with precise line and column numbers so you can fix malformed JSON without hunting through nested braces.
Frequently Asked Questions
How do I format JSON online?+
Paste your JSON into the editor, and JSON Mint formats it instantly with proper indentation. Choose 2-space, 4-space, or tab indentation using the buttons above the editor.
Is my JSON data private?+
Yes. Everything runs entirely in your browser. Your JSON is never uploaded to a server, stored, or logged. You can even use JSON Mint offline after the first load.
What if my JSON has a syntax error?+
JSON Mint shows the exact line and column of the error with a human-readable message. Click the error to jump your cursor to the problem.
Is there a size limit?+
There's no hard limit, but very large files (tens of MB) may slow your browser since parsing happens locally. For most API responses and config files, performance is instant.
Is JSON Mint free?+
Yes. All tools are free with no signup and no rate limits. The site is supported by unobtrusive display ads.
Can I minify JSON here too?+
Yes — use the dedicated JSON Minifier page to compress JSON to a single line and see the size savings instantly.