JSON Formatter & Validator
Free online JSON formatter and validator — beautify, minify and error-check JSON instantly in your browser. Nothing is uploaded.
Why you’ll love JSON Formatter & Validator
Instant & free
No signup, no paywall, no limits — JSON Formatter & Validator works the moment the page loads.
Completely private
Everything runs in your browser. Nothing you enter is ever uploaded or stored on a server.
Works on any device
Fully responsive and touch-friendly — use it on your phone, tablet or desktop.
Made for makers
Fast, keyboard-friendly and precise — handy for writers and developers alike.
How to use it
Open it
No download and no login — the tool is ready right at the top of this page.
Use it
Enter your details or start interacting. Everything updates live as you go.
Get your result
Copy, download or share your result in a single tap. That’s it.
About JSON Formatter & Validator
This JSON formatter and validator runs entirely in your browser — the text you paste is never uploaded or logged anywhere. That matters more for JSON than for most data, because real-world payloads are full of API keys, bearer tokens, session IDs and customer records. Here they never leave your machine.
Paste any JSON and choose one of three actions. Beautify re-indents it with two spaces per level so nested objects and arrays become readable. Minify strips every insignificant space and newline back to a single compact line, which is what you want for production payloads and config you ship over the wire. Validate checks the text without changing it and reports either a green "valid" confirmation or the exact parser error message.
Validation uses the browser's native JSON.parse — the same strict RFC 8259 parser JavaScript itself uses — so if this tool accepts your JSON, your code will too. That strictness is the point: trailing commas, single quotes, unquoted keys and comments are all legal in JavaScript but illegal in JSON, and they are the errors this tool catches most often. One-click copy puts the result on your clipboard when you are done.
Popular uses
Frequently asked questions
The four most common causes are a trailing comma after the last item, single quotes instead of double quotes, unquoted property names, and comments. All four are fine in a JavaScript object literal but forbidden in JSON, which is why config copied out of JS code so often fails. The error message comes straight from the browser's parser and usually names the offending character.
Yes. The formatter is pure client-side JavaScript — there is no server round-trip, no analytics on the content, and nothing is stored. Formatting, minifying and validating all happen in your browser's memory, so pasting a payload with credentials in it exposes nothing.
Values and key order are preserved exactly as parsed, with one JavaScript quirk: purely numeric keys (like "2", "10") are re-sorted numerically ahead of other keys, because that is how JS engines order object properties. String keys keep their original order.
JSON.parse stores every number as a 64-bit float, so integers above 9,007,199,254,740,991 (2^53 − 1) lose precision when re-serialized — a common surprise with 64-bit database IDs like Twitter/X snowflake IDs. If an API sends IDs that large, they should be transmitted as strings; the formatter cannot recover precision the parser already discarded.
Validate only checks the text and leaves it untouched — useful when you must not modify the original. Beautify (and Minify) parse and rewrite the text, so they double as validation: if the JSON is broken you get the same error message and nothing is changed.
JSON Formatter & Validator is 100% free — no signup, no watermarks and no usage limits. It’s one of 200+ free tools we build and give away.
No practical limit — it all runs in your browser, so paste as much as you need.
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