JSON Builder / Formatter
Create JSON from typed fields or paste JSON to validate and format it. Errors are shown before you copy the result.
Your result
Fill the fields and run the tool. Your input stays in this browser session.
Ready when you are.
What this tool does
Create JSON from typed fields or paste JSON to validate and format it. Errors are shown before you copy the result.
Example
Example: name | string | Ada and active | boolean | true produce a valid object with correct value types.
How to use it
Choose Build or Format. In Build, add one field per line as name | type | value. In Format, paste a JSON object or array. Review errors and copy the valid output.
Useful for
API payload drafts, structured AI output examples, test fixtures and MCP configuration preparation.
Limitations
The builder creates a flat object. Nested objects and arrays can be entered with the json type or formatted in the second mode.
FAQ
Does it upload my JSON?
No. Validation and formatting run in your browser.
Can it repair invalid JSON automatically?
No. It reports the parser error so you can correct the source intentionally.
