JSON Formatter / Validator
Format, minify, and validate JSON with 2-space, 4-space, or tab indentation — all in your browser.
About the JSON Formatter / Validator
The JSON Formatter / Validator takes raw, messy, or minified JSON and turns it into clean, readable, correctly indented output — or collapses it back down into a single compact line. It also checks whether your JSON is actually valid and, if it isn't, tells you exactly what went wrong and where. Everything runs directly in your browser using the same JSON engine the browser itself uses, so there is no upload, no waiting on a server, and nothing you paste ever leaves your device.
Developers reach for a JSON formatter constantly. API responses often arrive minified into one enormous line that is impossible to read; log files and config files drift out of shape; and a single missing comma or stray trailing bracket can break an entire request. Pretty-printing the data makes its structure obvious at a glance — you can see nesting, spot the key you need, and confirm arrays and objects are closed properly. When you're ready to ship the payload, minifying strips every unnecessary space and newline so the JSON travels as small as possible.
How to use
- Paste your JSON into the Input box. It can be pretty-printed, minified, or anything in between — the tool reads it either way.
- Pick an indent style — 2 spaces, 4 spaces, or tabs. Two spaces is the most common convention; tabs suit teams that prefer them for accessibility or personal settings.
- Click Format to pretty-print. The parsed, re-indented result appears in the read-only Output box, and a small "Valid JSON" confirmation shows above it.
- Click Minify to collapse the JSON into one line with no extra whitespace — ideal for pasting into a request body or storing compactly.
- Click Validate to check the JSON without changing it. If it's well-formed you'll see the "Valid JSON" badge; if not, a red message shows the exact parse error reported by the JSON engine.
- Copy the output with the Copy button, or hit Clear to empty both boxes and start over.
If your JSON is invalid, the Output box stays empty and an inline error explains the problem — for example an unexpected token, an unterminated string, or a position where the parser gave up. Fix that spot in the input and run the action again.
Frequently asked questions
Is my JSON uploaded or stored anywhere?
No. All parsing, formatting, minifying, and validation happen locally in your browser with JavaScript. Your data is never sent to a server, saved, or logged. Close the tab and it's gone — which makes the tool safe for internal API responses, tokens, or any sensitive payload.
What does "Valid JSON" actually check?
It runs your text through the browser's built-in JSON parser (the same JSON.parse engine used by real applications). If it parses without throwing, the JSON is structurally valid: quotes, commas, brackets, and braces all line up. Note that valid JSON only means the syntax is correct — it does not check that the data matches a particular schema or business rule.
Why does it reject JSON that looks fine to me?
Strict JSON has rules that trip people up. Keys and string values must use double quotes, not single quotes. Trailing commas after the last item in an object or array are not allowed. Comments (// or /* */) are not valid JSON. And special values like NaN, Infinity, or unquoted words aren't permitted. The error message points you to the offending spot.
What's the difference between Format and Minify?
Format (pretty-print) adds line breaks and indentation so the structure is easy to read and diff. Minify does the opposite: it removes all non-essential whitespace to produce the smallest possible single-line string. Both produce semantically identical JSON — only the whitespace differs — so you can switch between them freely.
Does formatting change my data?
No. The tool parses your JSON into an in-memory value and re-serializes it, so key/value pairs and array items are preserved exactly. Only whitespace changes. Be aware that object key order is kept as written, and duplicate keys collapse to the last one — that's standard JSON parsing behavior, not something this tool adds.
Which indent option should I choose?
Two spaces is the de facto default for most JavaScript, TypeScript, and web projects and keeps deeply nested data compact. Four spaces gives more visual separation for complex structures. Tabs let each viewer's editor decide the visible width, which some teams prefer for accessibility. Pick whichever matches your project's style guide — the choice only affects the pretty-printed output.