API Doc Previewer
Fill in endpoints, parameters and response examples through forms, and instantly generate a Markdown API doc, an OpenAPI 3.0 YAML spec and a rendered preview. No coding needed.
FreeOnline Tool
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How to Use
Enter the API name, version and Base URL, then use the endpoint list to set each endpoint's method (GET, POST, PUT, PATCH or DELETE), path and description. Add Query and Body parameters with name, type, required flag, description and example, and paste the JSON response example. Click 'Generate preview' and switch between the 'Markdown', 'OpenAPI 3.0 (YAML)' and 'Rendered' tabs to see the source, the spec and a rendered document. Add or remove endpoints anytime, or load the sample data to explore.
Features
- Form-based editing of endpoints, parameters and response examples
- One-click Markdown API documentation output
- OpenAPI 3.0 (YAML) spec generated in parallel
- Built-in lightweight renderer for a visual preview
- Query and Body parameters with required marks and example values
Use Cases
Ship API docs fast
Enter endpoints before integration starts and produce a clean Markdown doc in minutes to share with frontend and backend colleagues
Export an OpenAPI spec
Copy the generated OpenAPI 3.0 YAML straight into Swagger UI or an API management platform
Document legacy systems
Capture legacy endpoints in a uniform format for handover, search and maintenance
Keep doc style consistent
Generate every service doc with the same structure so parameter tables and descriptions look alike across the team
FAQ
Do I need to write code?
No. Everything is entered through forms and the tool generates Markdown and OpenAPI YAML for you, so anyone can produce API docs
Is the generated OpenAPI complete?
It is a solid, usable OpenAPI 3.0 skeleton covering info, servers, paths, parameters, requestBody and response examples, which you can extend further
Which parameter types are supported?
string, integer, number, boolean, array and object, selectable in each parameter row
Does the rendered preview match real Markdown?
The preview uses a built-in simplified renderer covering headings, bold, inline code, tables and code blocks. For complex Markdown, rely on the source shown in the Markdown tab