Drawpenapi — OpenAPI diagram editor
Design an HTTP API visually, in sync with your OpenAPI YAML file. Drawpenapi shows the API the way
Swagger UI does — tags, operations, schemas — and makes every part of it editable. Edit the diagram
and the YAML changes; edit the YAML and the diagram changes.
This is the Drawpenapi web editor, running inside Visual Studio
on the files of your solution or folder. Requires Visual Studio 2022 (17.14 or later) or Visual Studio 2026.
Use it
- Open or select an OpenAPI 3.0, 3.1 or 3.2 file (
.yaml or .yml).
- Right-click it in Solution Explorer, its document tab or the code editor and choose Open
Drawpenapi Diagram Editor (or … to the Side). Open With… → Drawpenapi Diagram Editor
works too, and Set as Default there opens YAML files in Drawpenapi from then on.
- Edit on either side. The text editor and the diagram follow each other as you type. From the
diagram's tab, Open Text Editor to the Side shows the YAML next to it.
The file stays an ordinary YAML file. Save, undo, reload and source control all work the way they do
for any other file: Ctrl+S saves it and Ctrl+Z undoes the last change, whichever side made it.
What you can do
- Add, edit, reorder and delete operations, parameters, request bodies, responses and webhooks.
- Edit schemas, security schemes and every other component type, with references kept whole.
- See problems (dangling references, missing fields) listed as you work.
- Export the API sheet as SVG, PNG or PDF.
Good to know
- A diagram edit rewrites the file in Drawpenapi's own formatting. Every field and extension the
document holds is kept, but fields are written in a standard order, quoting and spacing become
uniform, and YAML comments are not kept. Drawpenapi asks before it rewrites a file it did not
write, once per file. Edits you type in the text editor are never reformatted.
- A file that is not an OpenAPI 3.x document (Swagger 2.0, a YAML syntax error) is not opened as a
diagram, and is left untouched. Fix it in the text editor and the diagram appears by itself.
- A new, empty file opens as an empty API. Nothing is written until your first edit.
- OpenAPI documents written as JSON are not supported here: the editor writes YAML.
Privacy
Drawpenapi runs entirely inside Visual Studio. It makes no network requests, has no telemetry, and
reads and writes only the file you open with it. The editor's page is not allowed to contact any
server. Privacy policy · Terms of service
Feedback
drawdiags.com/contact
Part of the Free Diagrams suite: Drawmaid (Mermaid), Drawuml (PlantUML),
Drawtabase (SQL), Drawpenapi (OpenAPI) and Drawlize (JSON and YAML).
