JSON Formatter
Paste any JSON below. format it, validate syntax errors, or minify for production. Everything runs in your browser.
JSON Validator and Linter Online
Treat this page like a red build you need to unblock: paste the failing payload, hit validate, and read the first error with a line and column you can jump to in your editor. It is deliberately narrow: no minify wizardry, no schema inference, just strict JSON rules so you can answer "will JSON.parse accept this string?" before you merge. Pair it with JSON repair when the fix is mechanical.
How to Use
- Paste your JSON into the Input panel on the left
- Click Validate to check for syntax errors
- Review the error report: each issue shows the exact line and column number
- Fix the highlighted errors and re-validate until the JSON is clean
Features
- Instant JSON syntax validation against RFC 8259
- Precise error location reporting with line and column numbers
- Detects missing commas, trailing commas, unquoted keys, and single-quoted strings
- Clear pass or fail result displayed immediately after parsing
- Works on API responses, config files, and any JSON string
- Runs entirely in the browser. No uploads, 100% private.
- Free with no sign-up or account required
Frequently Asked Questions
What does JSON validation check?
JSON validation checks that a string conforms to the JSON specification (RFC 8259). It verifies that all keys are quoted with double quotes, values use only allowed types (string, number, boolean, null, object, array), commas correctly separate items, brackets and braces are balanced, and no trailing commas are present.
What is JSON linting?
JSON linting is the process of analyzing a JSON document for syntax errors and style issues. A linter goes beyond a simple pass-or-fail check: it reports the exact line and column of each problem and often explains what the parser expected to find instead, making errors much faster to fix.
Why does valid-looking JSON fail validation?
JSON has stricter rules than most developers expect. Common causes of failure include: single-quoted strings (JSON requires double quotes), trailing commas after the last item in an object or array, unquoted or numeric keys, JavaScript-style comments, and special control characters that must be escaped. Paste your JSON into the validator to see the exact reason and location of the error.
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