OpenAPI to Pydantic Converter — Generate Python Pydantic Models Online
OpenAPI to Pydantic
Convert OpenAPI 3 & Swagger specs (YAML/JSON) to Python Pydantic models
Generate clean Python Pydantic v1 and v2 BaseModel classes directly from OpenAPI 3.x and Swagger 2.0 specifications in YAML or JSON. Supports type hints, optional nulls, field aliases, and enum types.
Keywords: openapi, swagger, pydantic, python, fastapi, pydantic v2, baseModel, types
Tags: openapi, swagger, pydantic, python, fastapi, codegen, api, schemas
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OpenAPI to Pydantic is also known as: swagger to pydantic, openapi to python, openapi to pydantic v2, swagger to pydantic models, openapi pydantic generator.
How to OpenAPI to Pydantic Online
Paste your OpenAPI 3.x or Swagger 2.0 specification in YAML or JSON format into the editor.
Select your target Pydantic version: Pydantic v2 (recommended for modern FastAPI) or Pydantic v1.
Toggle Field Aliases if your API spec uses camelCase or kebab-case keys that should map to Python snake_case attributes.
Optionally set a class name prefix (e.g., Api) to namespace generated models.
Copy the generated Python code or download models.py directly for use in your FastAPI, Celery, or Django projects.
OpenAPI to Pydantic Features
Full OpenAPI 3.x & Swagger 2.0 Support: Seamlessly parses components.schemas and legacy definitions blocks in both YAML and JSON.
Pydantic v2 & v1 Native: Generates modern BaseModel classes with ConfigDict, model_config, and Field validation.
Automatic Pythonic Naming: Converts camelCase and hyphenated properties to PEP 8 snake_case with Field(alias="...") mapping.
Nested Object & Array Handling: Automatically extracts inline schemas into clean referenced child models.
Type Hints & Nullability: Accurately maps JSON Schema types to Python typing: str, int, float, bool, List[T], Dict[str, Any], and Optional[T].
Zero Telemetry Guarantee: Conversion runs 100% in your browser using client-side JavaScript. Private internal API contracts are never uploaded.
Pre-built Automation Pipelines
Chain OpenAPI to Pydantic with other utilities in a multi-step visual workflow.
Base64 Decode → JSON Format
Decode a Base64 string and pretty-print the JSON inside it.
CSV → JSON → YAML
Convert CSV data to JSON, then to YAML format.
JSON Format → TypeScript Schema
Format JSON and generate TypeScript/Zod schema from it.
Frequently Asked Questions
- How do I generate Pydantic models from OpenAPI in FastAPI?
- FastAPI natively uses Pydantic for request and response validation. By pasting your OpenAPI specification into this tool, you generate the exact Pydantic classes (models.py) you need to type request bodies, path responses, and query parameters in your FastAPI route handlers.
- Does this generator support Pydantic v2 syntax?
- Yes. Pydantic v2 is the default output format. It uses modern Python typing and Pydantic v2 constructs, but you can toggle Pydantic v1 compatibility at any time.
- Can I convert YAML OpenAPI specs without converting to JSON first?
- Yes. The parser natively handles YAML and JSON specifications without requiring external pre-conversion.
- Are my private API schemas or tokens sent to any server?
- No. DevFlow runs the entire parsing and code emission pipeline client-side in the browser. No schemas or data ever leave your computer.
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