Custom APIs

Beyond the catalog, you can monitor any API by providing its documentation URL.

Adding a custom API

Click Custom API in the dashboard sidebar
Enter a name for the API (e.g., "Internal Payments API")
Paste the documentation URL — this can be:
- An OpenAPI/Swagger spec URL (JSON or YAML)
- An HTML documentation page
- A markdown docs page
Choose a check interval:
- Every 24 hours — available on all plans
- Every hour — requires Pro plan
Click Add API

Varen will fetch the URL, detect the format, and begin monitoring.

Format	Detection	Quality
OpenAPI 3.x (JSON/YAML)	Deterministic diff	Highest — exact endpoint, parameter, and schema changes
Swagger 2.0 (JSON/YAML)	Deterministic diff	High — same as OpenAPI 3.x
HTML documentation	AI-powered analysis	Good — catches most changes, may miss subtle ones
Markdown / plain text	AI-powered analysis	Good — same as HTML

For best results, use an OpenAPI spec URL when available. Deterministic diffing is more reliable than AI-powered analysis.

Plan	Custom APIs
Hobby	Up to 3 total monitors (catalog + custom)
Pro	Up to 15 total monitors

Use the raw spec URL, not the rendered docs page. For example, use https://api.example.com/openapi.json instead of https://docs.example.com.
Avoid URLs behind authentication. Varen needs public access to fetch the documentation.
Check the format detection. After adding, verify in the API detail page that Varen correctly detected the documentation format.