JSON formatter and validator free
Pretty-printing, minification and syntax checking — right in the browser, no data sent anywhere.
From a blob to readable structure
How to format JSON in 4 steps
An API response, config or export — any size.
Indentation and line breaks appear.
One whitespace-free line for transport.
Syntax errors show with a position.
Part of the Zerocoder platform
One tool of a platform where AI generates websites, images, video, text and documents — under one subscription.
JSON is the language of integrations: API responses, configs, webhooks, data exports. It usually arrives as one unreadable line. The formatter adds indentation, the minifier squeezes it back, the validator shows the first error with its position — exactly as the standard parser sees it. Everything in the browser: data never leaves the page, so production keys and sensitive payloads are safe. Integrating AI into your product? See the Zerocoder API: one key for every model. The rest of the free tools are in one section.
Common JSON errors and how to read them
The three champions: a trailing comma after the last element (forbidden in JSON), single quotes instead of double, and unescaped line breaks inside strings. The validator surfaces the parser's message with a character position — go there and look at the character before it: the bug almost always lives there. Comments are forbidden too — JSON isn't JavaScript.
Format or minify: when to use which
Formatted JSON is for humans: debugging an API response, reviewing a config, writing docs. Minified is for machines: saves bandwidth and log space, fits into one curl line. The rule: store and transmit minified, read and edit formatted. The buttons switch back and forth losslessly.
Why in-browser processing matters
API responses often carry tokens, personal data and business information. Online formatters that route data through their servers are a leak risk. Here your own browser does the parsing with standard JSON.parse: data physically never leaves the tab. Check the network inspector — there are no requests.
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FAQ
Is my data uploaded?
No: parsing and formatting run in the browser. Safe for keys and production payloads.
What does the validator show?
The first syntax error with a message and position — as the standard parser sees it.
What errors are most common?
A trailing comma, single quotes, unescaped line breaks inside strings.
Can it handle big files?
Megabyte JSON formats instantly — the tab's memory is the only limit.
Are comments allowed in JSON?
No, the standard forbids them — the validator will flag it.
Does it sort keys?
No, key order is preserved.
Do I need an account?
No: the formatter runs in your browser with no limits.
Why minify at all?
Less bandwidth, compact logs, JSON fits into a one-line command.
What else does Zerocoder do?
An API to every AI model with one key, code and text generation, courses. The formatter is one free utility.