JSON Schema Generator
Infer a JSON Schema from example data in one click.
- 100% client-side · your data never leaves your browser
- Instant, no rate limits
- Free, no sign-up
Your result appears here
Paste JSON into the panel on the left — everything runs privately in your browser.
Overview
JSON Schema Generator — Infer Schema from JSON
Generate a JSON Schema from example JSON in one click. JsonDrift infers types, properties, required fields, and nested object shapes from a sample document — ideal for API documentation, contract tests, OpenAPI components, and LLM structured-output specs. Stop hand-writing schemas from scratch when a golden sample already exists.
What is JSON Schema?
JSON Schema is a vocabulary for describing valid JSON structure: which keys exist, what types they have, allowed enums, array constraints, and nested object rules. OpenAPI 3.1 aligns with JSON Schema. Function-calling and structured-output APIs increasingly accept schema definitions to constrain model output.
How inference works
The generator walks your sample JSON recursively. Strings become { "type": "string" }, integers become integer, arrays produce items schemas merged from observed elements, and objects list every seen key in properties and required.
The inferred schema is strict: additionalProperties is false and all observed keys are required — excellent for validation gates; relax manually if your API allows extra fields.
Schema-first API workflows
- Document request/response bodies alongside OpenAPI
- Validate fixtures in CI before merge
- Define LLM tool parameters and structured outputs
- Catch config drift in microservice settings
After generation
Review the schema in the JSON Schema Validator with edge-case payloads. Add enums, string formats (email, uuid), and min/max constraints the sample alone cannot infer. Store schemas in git and validate PRs automatically.
FAQ
Frequently asked questions
Is the generated schema strict?
Yes by default: all seen keys are required and additional properties are disallowed. Edit the schema to loosen rules if needed.
Can one sample represent optional fields?
Optional fields absent from the sample will not appear. Provide samples with and without optional keys or edit the schema manually.
Which JSON Schema version?
Output uses common Draft-style keywords compatible with most validators and OpenAPI 3.1 tooling.
Does generation upload my API data?
No. Inference runs locally in your browser.
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