JSON Formatter and Validator
Pretty-print and validate JSON, with the exact error location. Free to use, no signup required for occasional use.
Formatted JSON will appear here…What is the JSON Formatter & Validator?
The JSON Formatter & Validator is a free online tool that takes messy, minified, or hand-typed JSON and turns it into clean, indented, easy-to-read output, while also checking it for syntax errors. JSON is the backbone of most modern APIs, config files, and data exchange between services, but a single missing comma, stray bracket, or unescaped quote can make an entire payload invalid — and the raw error messages from most parsers are cryptic and hard to act on. This tool parses your input using a strict JSON parser and, if the JSON is invalid, reports the exact line and column where parsing failed so you can jump straight to the problem instead of scanning the whole document by eye. If the JSON is valid, it re-serializes it with consistent 2-space or 4-space indentation, making nested objects and arrays far easier to read and review. Developers, QA testers, and anyone debugging an API response, webhook payload, or configuration file can paste raw JSON in, confirm it's well-formed, and get a formatted version ready to share, log, or paste into documentation. Because everything runs through a standard, spec-compliant JSON parser, the validation results match what any JSON-consuming service will actually accept or reject.
How to use it
Paste your JSON — whether it's minified, partially formatted, or hand-written — into the input box. Click 'Format' with either 2-space or 4-space indentation, whichever matches your project's style. If the JSON is valid, the formatted, indented version appears immediately in the result panel, ready to copy with the copy button. If there's a syntax error, the tool tells you the exact line and column where parsing broke, along with the underlying parser message, so you can find and fix the issue in your original source (for example, in your editor or API client) rather than guessing. After fixing the problem, paste the corrected JSON back in and format it again to confirm it now parses cleanly. This workflow is especially handy when debugging API responses copied from browser dev tools, reviewing a teammate's config file, or cleaning up JSON that was generated programmatically without consistent formatting.
Frequently asked questions
Does the formatter tell me exactly where a JSON error is?
Yes. When your JSON is invalid, the tool reports the specific line and column where the parser failed, along with the parser's error message.
Can I choose the indentation style?
Yes, you can format with either 2-space or 4-space indentation depending on your project's conventions.
Does formatting change the actual data in my JSON?
No, formatting only changes whitespace and indentation. The underlying keys, values, and structure of valid JSON are preserved exactly.
Can I validate very large JSON payloads?
Yes, you can paste large API responses or config files; the tool parses and formats the full document in one pass.