JSON Formatter & Validator
Pretty-print messy JSON, minify it for production, or find out exactly why it won't parse — all locally in your browser.
Input
Output
🔒 Runs in your browser — nothing is uploaded to a server.
What this tool does
- Format — pretty-print JSON with 2 spaces, 4 spaces or tabs.
- Minify — strip all insignificant whitespace for the smallest payload.
- Validate — get a precise parser error (line and reason) when the JSON is invalid.
Common JSON errors
- Trailing commas —
[1, 2, 3,]is invalid JSON, even though it's allowed in JavaScript. - Single quotes — JSON requires double quotes for both keys and string values.
- Unquoted keys —
{foo: 1}is JavaScript, not JSON; it must be{"foo": 1}. - Unescaped control characters — raw newlines inside a string must be escaped as
\n.
Why format JSON in the browser?
JSON often contains API keys, customer records or other sensitive data. Formatting it locally means it never leaves your machine — no upload, no logs, no third-party server.
Working with data every day?
If you move data between tools regularly, these automate the parts this converter can't:
- Zapier — connect the apps your data lives in
- Airtable — a spreadsheet-database for teamwork
- Coefficient — sync live data into Google Sheets & Excel
Some links may be affiliate links. Replace these placeholders with your own affiliate URLs before launch.