Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Format, validate, and pretty-print JSON, with clear syntax-error locations.
Enter valid JSON to see formatted output, a tree view, and a minified version.
Minified or poorly-formatted JSON -- common in API responses and config files -- can be nearly unreadable as one long line. This tool validates your JSON, pretty-prints it with proper indentation, and if there's a syntax error, pinpoints exactly which line and column it's on, rather than a vague "unexpected token" message.
Paste your JSON into the input box. Valid JSON is formatted instantly with clean indentation. If the JSON is invalid, an error message shows the specific problem and its exact line/column location, so you can jump straight to the issue instead of scanning the whole document.
This tool uses a dedicated character-by-character scanner that walks through the JSON grammar (objects, arrays, strings, numbers, literals) to find the exact offset where the structure breaks down, then converts that offset into a line and column number -- giving you a precise location rather than relying on a browser's own generic parser error text.
Debugging a malformed API response or config file where a missing comma or unclosed bracket is hard to spot by eye. Formatting minified JSON into a readable structure for documentation or debugging. Validating a JSON payload before sending it in a request.
Once your JSON is valid, the tool offers a tree view, a formatted view, and a minified view. The tree view is best for exploring nested structures, such as an API response with arrays of objects, because you can see the hierarchy without scanning brackets. The formatted view is the version to copy into documentation, code review comments, or a config file, where consistent indentation makes differences easy to spot. The minified view removes all optional whitespace, which is useful when you need a compact string for a request body, a query parameter, or a test fixture.
Consider a small hypothetical object where a comma is missing between two properties on separate lines, for instance a name property followed directly by an age property. The scanner reaches the second key where it expected a comma or a closing brace and reports the line and column of that position. The reported spot is where the parser noticed the problem, which is often just after the actual mistake, so look at the end of the previous line as well. Fix the comma, and the output appears immediately, confirming the whole document now parses.
JSON numbers are usually read by programs as double-precision floating point. Very large integers, such as long identifiers, can lose precision once parsed in JavaScript. If an ID looks slightly different after you process it in your own code, store it as a string in the JSON instead. Leading zeros (like 007) are not allowed for numbers, so quote them if the zeros matter.
Formatting happens in your browser, but you should still avoid pasting live secrets such as API keys or tokens into any tool when you can substitute placeholders. Sanitize sample data before sharing it with others.
A document can be perfectly valid JSON and still be wrong for your application: a missing required field, a string where a number is expected, or an unexpected nesting level will all pass a syntax check. Use a schema validator or your application's own tests to check structure and meaning.
Common causes include a trailing comma after the last item in an object or array (not allowed in strict JSON), unescaped quotes inside a string, or using single quotes instead of double quotes for keys/strings -- the error location this tool shows should point you to the exact spot.
No -- this validates that your input is syntactically correct JSON (proper structure/grammar), not that it matches any particular expected schema or shape.
Not in standard JSON. Remove comments before validating, or use a format that supports them if you need annotations.
The scanner reports where the structure breaks, which is often the next token after a missing comma or quote. Check the end of the previous line too.
Yes. Modern JSON allows any value at the top level, including strings, numbers, true, false, and null, not only objects and arrays.
Large integers can lose precision when parsed as floating-point numbers. Store such identifiers as strings.