JSON Formatter & Validator
Beautify, validate and minify JSON with precise, actionable syntax error reporting.
How to Format, Validate and Minify JSON in the Browser
JSON is easy for machines to parse and genuinely painful for humans to read once it arrives minified from an API. A JSON formatter re-indents that single dense line into a readable tree, and — just as usefully — tells you precisely where the syntax broke when a payload will not parse at all.
This formatter uses the browser’s own JSON.parse(), which means validation is exactly as strict as the parser your code will use in production. When parsing fails, the error is reported with the line and column number and the offending snippet, so you can jump straight to the problem instead of hunting for a missing comma.
Key features
- Strict validation — powered by the native JSON parser, so what passes here passes in your application.
- Pinpointed error reporting — line and column numbers plus the surrounding text for every syntax error.
- Configurable indentation — 2 spaces, 4 spaces or tabs.
- One-click minify — strip every byte of optional whitespace for production payloads.
- Key sorting — optionally sort object keys alphabetically to make two payloads diffable.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: JSON Formatter & Validator
- Paste your JSON
Drop raw JSON into the input pane — minified, malformed or already formatted, it does not matter. - Click Format
Valid JSON is re-indented into a readable tree. Invalid JSON produces an error banner naming the exact line and column. - Fix any reported errors
The most common causes are trailing commas, single quotes instead of double quotes, and unquoted object keys — none of which are legal JSON. - Copy or minify the result
Copy the formatted output for documentation, or click Minify to produce the smallest valid payload for transmission.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Developer |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
Why is my JSON invalid when it looks correct?
The three usual culprits are a trailing comma after the last element, single quotes around strings or keys, and unquoted keys. All three are valid JavaScript object literals but none of them are valid JSON, which requires double quotes and forbids trailing commas.
Does formatting change my data?
No. Formatting only adds or removes insignificant whitespace between tokens. Key order is preserved unless you explicitly enable alphabetical sorting, and no value is ever altered.
Is it safe to paste production data here?
Yes. The JSON is parsed by your own browser and never leaves the page — there is no server request, no logging and no analytics on the content you paste.
What is the difference between minifying and formatting?
They are inverse operations. Formatting adds indentation and line breaks for human readability; minifying removes every optional byte to make the payload as small as possible for storage or transfer.