JSON Schema Generator Online

What is JSON Schema?

JSON Schema is a vocabulary for annotating and validating JSON documents. It describes the shape of JSON data — what fields exist, their types, which are required, and constraints like format or additional properties.

Which JSON Schema draft does this tool generate?

You can choose between Draft-07 (the most widely supported version, used by OpenAI function calling) and Draft 2020-12 (the latest standard). Both are available via the options panel.

Does it detect formats like email, UUID, or date automatically?

Yes. When "Infer types & formats" is enabled, string values are checked against common patterns and assigned format keywords like email, uuid, date, date-time, and uri.

What does "Additional properties: false" do?

Setting additionalProperties to false in a schema means that JSON objects must not contain any properties beyond those explicitly listed. This is required for OpenAI structured outputs and is good practice for strict API validation.

Can I use the generated schema with OpenAI function calling?

Yes. Use Draft-07, enable "Mark all fields required", and enable "No additional properties" — these settings match what OpenAI expects for function and tool definitions.

Does this handle nested objects and arrays?

Yes. The generator recursively processes nested objects and arrays of any depth, producing the correct nested schema structure.

Is my JSON sent to a server?

No. All schema generation runs locally in your browser using JavaScript. Nothing is uploaded.