Document an API payload
Create an initial schema while documenting an existing request, response or event format.
100% local · files never leave your browser
Generate tool
JSON Schema Generator
Generate a practical JSON Schema from sample JSON locally in your browser. Review inferred types and required fields before use.
✓ Free to use✓ No signup✓ Runs locally
160 bytes · local only
Waiting
♢
Processed entirely in this tab
Your input and result are not sent to JSON Hearth or stored on a server.
When to use it
What Schema Generator helps you do
Schema inference turns a representative JSON example into a starting contract. It can save time, but the result should be reviewed against real business rules.
Bootstrap validation
Generate a first draft before adding required fields, ranges, patterns and descriptions manually.
Understand sample data
Summarize nested types and properties in a machine-readable form.
Important limitations
What to check before using the result
- One example cannot reveal every optional field, allowed value or future variation.
- Inferred required fields and types must be reviewed before production validation.
Common questions
About Schema Generator
Is an inferred JSON Schema production-ready?
Treat it as a draft. Add domain rules and test it against multiple valid and invalid examples.
Can the generator detect optional fields?
A single sample cannot reliably distinguish optional fields from fields that simply happened to be present.