JSON Formatter & Syntax Validator
Check JSON syntax and create readable or compact output without rounding numeric identifiers.
Choose JSON, then select readable, compact or validation-only output.
A clear result starts here
Run the tool to see your output here.
Try the example to explore how it works.What to know about this tool
Up to 2 MB and 200 nesting levels; expanded output up to 8 MB. Number/string tokens and duplicate properties are preserved, with duplicate warnings. No schema validation, JSONC or automatic repair.
Instructions and examples
From input to output
- Choose JSON or open the optional paste area.
- Choose Readable JSON, Compact JSON or Validate only, and set Indent spaces for readable output.
- Select Check and format JSON, inspect syntax feedback and warnings, then copy or download the result.
Settings and result behavior
- Readable and compact modes change whitespace while preserving original number and string tokens.
- Validate only reports syntax status rather than producing reformatted JSON. It does not check an application schema.
- Duplicate properties remain in formatted output with a warning; other parsers may discard them.
A worked example
- Input
{"id":9007199254740993,"ready":true}- Settings
- Readable JSON; Indent spaces 2.
- Expected result
{ "id": 9007199254740993, "ready": true }
Supported input and limits
Choose a UTF-8 JSON or TXT file, or open “Paste JSON instead”. Use standard JSON with double-quoted strings, no comments and no trailing commas. Formatting is limited to 2 MB input, 200 nesting levels and 8 MB expanded output.
Up to 2 MB and 200 nesting levels; expanded output up to 8 MB. Number/string tokens and duplicate properties are preserved, with duplicate warnings. No schema validation, JSONC or automatic repair.
If the result is unexpected
- For a syntax error, inspect the reported position and nearby quotes, commas and brackets. The tool does not automatically repair them.
- For output expansion limits, reduce indentation, choose Compact JSON or use a smaller file.
Check before using the result
Resolve duplicate-property warnings before passing data to another parser. Valid JSON syntax does not establish safe content, required fields or correct business values.
Report a problem with this tool. Include a nonsensitive example and your browser details.
Questions about this tool
Does validation repair JSON or check a schema?
No. This workspace checks standard JSON syntax and formats or minifies valid input. It preserves numeric tokens and warns about duplicate properties. JSONC, automatic repair and JSON Schema validation are not supported.