Is my JSON uploaded anywhere?

No. Parsing, validation and formatting all happen in your browser with JavaScript — the data never leaves your device, nothing is logged, and the tool keeps working offline once the page has loaded. That matters because JSON often contains API keys, tokens and customer data.

How do I find the error in my JSON?

Paste the text and the validator points to the exact line and column of the first syntax error, along with the parser’s message. Fix that spot, and if there is another error further down, it will be reported next — JSON parsers stop at the first problem they hit.

What are the most common JSON syntax errors?

Trailing commas after the last item, single quotes instead of double quotes, unquoted keys, missing commas between items, and comments (JSON does not allow // or /* */). JavaScript object literals accept these — strict JSON does not.

What does minify do and when should I use it?

Minifying removes all whitespace and newlines, producing the smallest possible payload — useful for config values, HTTP requests and storage. Formatting (pretty-printing) does the opposite: it adds indentation so humans can read the structure. Both outputs are exactly equivalent data.

What does “sort keys” do?

It recursively sorts every object’s keys alphabetically. Sorted JSON is much easier to compare in code reviews or with a diff tool, because two files with the same data always end up in the same order. Try pairing it with our diff checker.

Is there a size limit?

There is no hard limit — the tool processes whatever your browser’s memory can handle, and multi-megabyte files are fine on a typical laptop. Since nothing is uploaded, size costs you no bandwidth either.

Does it validate against a JSON Schema?

No — this tool checks syntax (is it valid JSON at all?), not schema conformance (does it have the fields your API expects?). Schema validation needs your specific schema file and is a different job. For syntax, error location and formatting, this does everything locally and instantly.

JSON Formatter & Validator

Format, validate and minify JSON with exact error line & column — everything runs in your browser.

Files never leave your device Instant — no upload waitFree, no sign-up

Paste JSON

Output style

Sort object keys alphabetically

Format, validate and minify JSON — without pasting secrets into a random server

JSON is the language of APIs, and sooner or later everyone stares at a wall of unformatted JSON wondering where the missing comma is. This JSON formatter and validator fixes that in one paste: it tells you instantly whether the text is valid, points to the exact line and column of the first error, and pretty-prints the structure with 2 spaces, 4 spaces or tabs — or strips it down to a minified single line for production payloads.

Everything runs in your browser

JSON frequently contains things that should never leave your machine: API keys, session tokens, customer records, internal URLs. Most online formatters send your paste to their server. This one doesn’t — parsing and formatting happen entirely on your device, and the page keeps working with the network unplugged. Paste with confidence.

Built for debugging

Beyond formatting, the tool shows useful shape information: how many keys the document has, how deeply it nests, and how many bytes the output weighs. The sort keys option orders every object alphabetically — do that to two responses and compare them in ourtext diff checker to spot what actually changed between two API calls.

Common errors it catches

Trailing commas, single quotes, unquoted keys, stray comments, truncated files — the classic ways JSON breaks when it is hand-edited or copied out of a log. The validator reports the parser’s real message, so what you see here matches what your code would throw in production.

Part of a free developer toolbox

Working with encoded payloads? Decode Base64 strings or inspectJWT tokens before formatting the JSON inside them. Converting data? TurnCSV into JSON or plain text into JSON and validate the result here. Every tool is free, unlimited and runs offline in your browser.

Frequently Asked Questions

Is my JSON uploaded anywhere?
No. Parsing, validation and formatting all happen in your browser with JavaScript — the data never leaves your device, nothing is logged, and the tool keeps working offline once the page has loaded. That matters because JSON often contains API keys, tokens and customer data.
How do I find the error in my JSON?
Paste the text and the validator points to the exact line and column of the first syntax error, along with the parser’s message. Fix that spot, and if there is another error further down, it will be reported next — JSON parsers stop at the first problem they hit.
What are the most common JSON syntax errors?
Trailing commas after the last item, single quotes instead of double quotes, unquoted keys, missing commas between items, and comments (JSON does not allow // or /* */). JavaScript object literals accept these — strict JSON does not.
What does minify do and when should I use it?
Minifying removes all whitespace and newlines, producing the smallest possible payload — useful for config values, HTTP requests and storage. Formatting (pretty-printing) does the opposite: it adds indentation so humans can read the structure. Both outputs are exactly equivalent data.
What does “sort keys” do?
It recursively sorts every object’s keys alphabetically. Sorted JSON is much easier to compare in code reviews or with a diff tool, because two files with the same data always end up in the same order. Try pairing it with our diff checker.
Is there a size limit?
There is no hard limit — the tool processes whatever your browser’s memory can handle, and multi-megabyte files are fine on a typical laptop. Since nothing is uploaded, size costs you no bandwidth either.
Does it validate against a JSON Schema?
No — this tool checks syntax (is it valid JSON at all?), not schema conformance (does it have the fields your API expects?). Schema validation needs your specific schema file and is a different job. For syntax, error location and formatting, this does everything locally and instantly.