JSON Formatter
Prettify, validate, and minify your JSON data with industrial-grade precision. High-performance formatting for massive datasets.
Ultra Fast
Optimized for processing large strings up to 50MB instantly.
Local Processing
Your data never leaves your browser. Privacy first formatting.
Syntax Rich
Smart error highlighting and structural visual cues.
How to Use the JSON Formatter
- Paste your JSON into the input pane on the left — minified API responses, log lines, config fragments, anything.
- Click Format. The formatted result appears in the output pane with consistent 2-space indentation.
- Switch to the Minify or Validate tab at any time — all three run on the same input without re-pasting.
- Click Copy to put the result on your clipboard, or Clear to start over.
Example: Formatting a Minified API Response
Input — minified JSON
{"id":204,"status":"shipped","items":[{"sku":"KB-201","qty":1},{"sku":"MS-330","qty":2}],"express":true}Output — formatted
{
"id": 204,
"status": "shipped",
"items": [
{
"sku": "KB-201",
"qty": 1
},
{
"sku": "MS-330",
"qty": 2
}
],
"express": true
}Every value, key, and array position is untouched — formatting only changes whitespace, never data.
What formatting changes — and what it never touches
Formatting re-indents structure only: nesting gets one 2-space level per depth, and each object key and array item moves to its own line. Key order, number precision, string contents, and unicode characters all pass through exactly as parsed. That makes it safe to format production payloads — the formatted document is semantically identical to the original.
Built for large payloads
Inputs over 200KB are formatted in a background Web Worker, so the page stays responsive instead of freezing while it works — and the same engine has been benchmarked against a 50MB JSON document. For most real-world API responses the result is effectively instant.
Frequently Asked Questions
Formatting re-indents JSON for readability without changing its data. Minifying does the opposite — it strips every insignificant space and newline to make the output as small as possible. Validating does neither; it only checks whether the JSON is syntactically correct and tells you where it breaks if not. This page gives you all three as tabs over the same input.
No — it parses strict JSON only (RFC 8259), the same rules as JSON.parse. Comments, trailing commas, single-quoted strings, and unquoted keys will all fail validation. If you need to work with JSON5 or JSONC (common in config files like tsconfig.json), strip the comments first.
It's been benchmarked with a 50MB JSON string and stayed responsive with no dropped frames — inputs over 200KB automatically run in a background Web Worker so the tab never freezes while formatting.
No. Parsing and formatting both happen entirely in your browser, in JavaScript — nothing you paste here is ever transmitted anywhere, which also means it keeps working if you go offline.
Standard JSON.parse errors are often vague (e.g. "Unexpected token") and don't say where the problem is. This tool locates the exact character offset the parser failed on and converts it to a line and column number, so you can jump straight to the broken bracket, quote, or comma instead of scanning the whole document.
Related Tools
JSON Beautifier
Pretty-print JSON with the same fast, local engine.
JSON Validator
Check JSON validity with precise line/column errors.
JSON Viewer
Explore JSON as a collapsible, searchable tree.
JSON Minifier
Strip whitespace to compress JSON for transport.
JSON Compare
Diff two JSON documents and highlight the changes.
JSON to CSV
Flatten nested JSON into a downloadable CSV file.