OpenAPI Class Explorer
DiagramsPaste an OpenAPI 3.x or Swagger 2.0 spec and instantly visualize all schemas as UML class diagrams with inheritance, composition, and $ref relationships mapped.
Load an OpenAPI / Swagger spec
JSON or YAML — OpenAPI 3.x or Swagger 2.x
Drop your spec file here
or click to browse — .json, .yaml, .yml
About OpenAPI Class Explorer
The OpenAPI Class Explorer parses your OpenAPI 3.x or Swagger 2.0 specification and automatically constructs a full UML class diagram of every schema defined in the `components/schemas` (or `definitions`) section. `$ref` cross-references become association arrows, `allOf` inheritance chains are drawn with generalization lines, and `oneOf`/`anyOf` unions are annotated clearly. Filter by name or toggle required-only to focus on the subset of your API that matters, then export the diagram as SVG, PNG, or Mermaid class-diagram syntax to share with your team or include in your API documentation.
Features
- ✓Parses OpenAPI 3.0, 3.1, and Swagger 2.0 YAML or JSON specs
- ✓Renders all `components/schemas` as UML classes with property types
- ✓Draws `$ref` associations as directed arrows between schema classes
- ✓Models `allOf` as UML generalization (inheritance) lines
- ✓Annotates `oneOf` and `anyOf` as interface/union notes
- ✓Filter panel to show/hide schemas by name or required-only properties
- ✓Export to SVG, PNG, or Mermaid class-diagram syntax
Common Use Cases
- Reviewing the data model of a third-party API before integration work
- Generating architecture diagrams for API-first design documentation
- Onboarding developers by providing a visual map of all API entities
- Auditing large OpenAPI specs for undocumented or orphaned schemas
- Comparing schema evolution between versions of an API spec
Frequently Asked Questions
QDoes the tool support both YAML and JSON OpenAPI files?
Yes. Paste or upload either YAML or JSON format. The parser auto-detects the format and processes both OpenAPI 3.x and Swagger 2.0 documents.
QHow are inline schemas (not in `components/schemas`) handled?
Inline request body and response schemas are extracted and given auto-generated names based on their operation ID and position so they appear in the class diagram alongside named schemas.
QCan I visualize only a subset of schemas?
Yes. Use the filter sidebar to search by schema name or toggle the "Required fields only" checkbox to show only schemas that have at least one required property. Only schemas matching your filter are rendered, making large APIs with hundreds of schemas manageable.
QWhat happens with circular `$ref` references?
Circular references are detected and rendered as dashed self-referencing arrows with a `[Circular]` label so the diagram remains valid without entering an infinite loop.