Words & text
JSON formatter & validator
Format, minify and validate JSON locally without changing large numbers.
How it works
JSON formatter & validator
JSON syntax is checked in your browser. Layout uses the original tokens rather than parsing and serializing numeric values.
How to use this tool
- Paste JSON and choose Format for two-space indentation, or Minify to remove whitespace outside strings.
- Read the validation message, then copy the output. Invalid input clears stale output so an earlier result is not mistaken for a new one.
Understanding the result
The tool checks JSON syntax and changes layout without rewriting number notation, key order, string escapes or duplicate keys. Large integers therefore remain exactly as typed in the output.
Worked examples
{"name":"InstaTool","free":true}
{"id":9007199254740993}
[1, {"text":"a b"}, null]
Good to know
Your JSON is not uploaded or saved. Syntax validity does not prove schema compliance.
Limit: 500,000 UTF-16 code units and 200 nesting levels. Comments, trailing commas, undefined and single-quoted strings are not JSON. Duplicate keys are preserved but should be avoided for interoperability. Formatted output is limited to 4,000,000 UTF-16 code units; try Minify for deeply indented input.
A few quick answers
Does valid JSON prove the data matches an API schema?
No. Syntax validation does not check required fields, types expected by an API or business rules. Validate those separately.
Sources and implementation
Implementation for this tool: JSON.parse · original tokens
Maintained by Chpl Limited · Updated: