Free JSON Schema Generator
Generate JSON Schema from sample payloads for API validation, AI tools, and typed interfaces.
About JSON Schema
Instantly derive a JSON Schema from any JSON object or array. Useful for OpenAI function calling, Anthropic tool use, and API contract validation.
Why generate JSON Schema?
JSON Schema is the standard for describing the structure of JSON data. It is required for AI function calling (OpenAI, Claude), API validation, form generation, and TypeScript type inference.
Key Features
- Auto Type Inference: Detects string, number, integer, boolean, object, and array types automatically.
- Format Detection: Identifies date-time, email, and URI string formats.
- Draft Support: Outputs Draft 2020-12, Draft 07, or Draft 04 schemas.
- Required Fields: Automatically marks non-null fields as required.
How to Use
- Paste a JSON sample into the left panel.
- Click Generate Schema to produce the JSON Schema.
- Copy the schema and use it in your API, AI tool definition, or validator.
Where It Helps
- Draft a starting schema from a real payload.
- Prepare structured parameters for tool-calling flows.
- Reduce manual mistakes before integration work begins.
What To Review Manually
This schema is inferred from examples. Optional fields, mixed arrays, strict constraints, and business rules should still be checked by hand.
Related Article
JSON Schema Guide for Developers - AI, APIs, and ValidationA practical guide to JSON Schema for API contracts, structured AI outputs, and validation workflows.