JSON Schema Generator

JSON Schema Generator - Infer Schema from JSON Online

Generate JSON Schema definitions automatically from your JSON data. Our tool infers types, required fields, and nested structures from a sample JSON document.

Paste a sample JSON object or array into the input field—this should be representative of the structure you want to define a schema for. Click generate, and the tool analyzes your JSON to infer types for each field, identifies required properties based on presence, and detects nested objects and arrays. The generated JSON Schema follows the Draft-07 specification and includes type definitions, required fields arrays, and nested schemas for objects. You can copy the schema for use in API validation, configuration files, or documentation. Edit the generated schema to add constraints like min/max values, enums, or pattern matching.

API developers create request and response validation schemas from sample API payloads. Backend engineers generate schema documentation for configuration files by feeding in examples. OpenAPI/Swagger users quickly build schema definitions for API specifications. Data validators bootstrap schema files for JSON data pipelines and ETL processes. Frontend developers create TypeScript interfaces by first generating JSON Schema then converting to types. Database designers model document structures for NoSQL databases like MongoDB or Couchbase.

Feed the generator comprehensive sample data that includes all possible fields and edge cases—sparse samples produce incomplete schemas. The inferred required fields may not match your actual requirements; review and adjust the "required" array manually. For union types (fields that can be multiple types), provide samples showing all variations or manually edit the schema afterward. Add validation constraints (minimum, maximum, pattern, minLength) manually since the generator only infers basic types. For production use, add descriptions to each field for better API documentation. JSON Schema Draft-07 is widely supported; check compatibility before using newer drafts.

All processing happens directly in your browser. Your files never leave your device — no server uploads, no cloud storage, no data retention. The tool works offline once loaded, requires no registration, and is completely free with no usage limits.