BracketJSON Formatter & Validator
Format, validate, and beautify JSON instantly. Catches syntax errors with line numbers. Runs entirely in your browser — nothing you paste is ever sent anywhere.
🔒 Runs entirely in your browser — no data is ever sent anywhereWhen you need a JSON formatter
API responses, application logs, and config files are often returned or stored as a single unbroken line of JSON — technically valid, but nearly unreadable by eye. Pasting that into a formatter re-indents it into a nested, human-readable structure so you can actually see where one object ends and the next begins, spot a missing field, or compare two payloads side by side. It's also the fastest way to check whether a JSON blob is valid at all before feeding it into code — a parser fails loudly and precisely rather than your application failing somewhere downstream with a less helpful error.
How this tool validates and formats JSON
Under the hood this uses JavaScript's built-in JSON.parse, the same parser every browser and Node.js runtime uses, so a syntax error caught here is a syntax error anywhere. If parsing fails, the browser's own error message — including the character position of the failure — is shown directly, which almost always points at a missing comma, an unquoted object key, or a trailing comma before a closing brace (all invalid in strict JSON, unlike JavaScript object literals). Once parsed successfully, JSON.stringify re-serializes the data with two-space indentation for the formatted view, or with no whitespace at all for the compact view — both are lossless round-trips of the exact same data, just formatted differently.
Frequently asked questions
Is it safe to paste sensitive JSON data here?
Yes. This tool runs entirely in your browser using JavaScript's built-in JSON.parse — your data is never sent to a server or stored anywhere, even temporarily.
What's the difference between formatting and validating JSON?
Validating just checks whether the JSON is syntactically correct. Formatting (also called 'pretty printing') additionally re-indents it with consistent spacing so it's easier to read. This tool does both at once — if it formats successfully, the JSON is valid.
Why does it show an error with a specific position?
JSON parse errors report the character position where parsing failed, which usually points to a missing comma, an unquoted key, or a trailing comma right before that position.
Related Data tools
Bracketly is free and open-source. If this tool saved you time, consider supporting it.
☕ Buy me a coffee