Validate and pretty-print JSON.
Validate JSON syntax and reformat valid data into readable indentation for debugging, configuration review and API work.
Best for: API responses, configuration snippets and copied JSON that is difficult to read on one line.
JSON has strict syntax: property names use double quotes, commas separate items, and comments are not part of standard JSON. Pretty-printing changes whitespace, not the underlying data.
Uses the browser’s native JSON.parse and JSON.stringify functions. Valid JSON is parsed into a data structure and then serialized with indentation; invalid syntax returns the parser error.
Use a schema validator when you need to check required fields, data types or business rules beyond syntax.
This section describes the implementation shipped with My Tools HQ. Verify important outputs before relying on them.
Got a different result? Report a problem with JSON Formatter. Include your browser, steps and expected result. Please do not send sensitive files.
Validity is about syntax. Pretty-printing only adds indentation and line breaks to valid data.
Standard JSON does not include a comment syntax, even though some configuration formats extend JSON with comments.
It should only change whitespace and presentation, not the parsed data values.
A debugging guide to quotation marks, commas, brackets, data types and misleading JavaScript syntax.