JSON Formatter Online
Format, minify and validate JSON in your browser with readable output and clear syntax errors.
Method and limitations reviewed August 3, 2026. Browser-first, no login required.
Your data is processed in your browser and not uploaded.
About this tool
What this tool does
The formatter validates JSON before producing an indented or compact representation. It is useful for reading API payloads and catching syntax errors before data is shared or committed.
How the result is produced
- Input is parsed with the browser's JSON parser; invalid syntax is rejected instead of being silently repaired.
- Formatted output uses two-space indentation.
- Minified output serializes the parsed value without presentation whitespace.
- Objects and arrays retain their parsed data structure, while insignificant source whitespace is removed.
Good uses
- Inspecting compact API responses
- Validating configuration snippets
- Producing readable examples for documentation or bug reports
How to verify the result
- Confirm numbers that require exact precision before using the browser parser.
- Check that duplicate object keys are not present in the source.
- Run schema validation separately when field types and required properties matter.
Known limitations
- Comments, trailing commas and JavaScript object literals are not valid JSON.
- Formatting checks syntax, not business rules or schema correctness.
- Duplicate keys can be overwritten during parsing and should be resolved at the source.