A lot of small SaaS APIs have decent docs. Some even have an OpenAPI spec. But no real sandbox. That sounds fine until a developer tries to integrate the API and needs to test the part that docs cannot prove: Does the workflow actually hold together? Not one request. The workflow. The problem is not the first 200 Most API docs can show this: POST /customers → 201 Created Enter fullscreen mode Exit fullscreen mode That is useful, but it is not enough. For a real SaaS integration, the next questions are usually: Can I read the same customer back? Does the subscription attach to the right customer? Does the webhook fire? Does my app know which user should get access? What happens when the subscription is canceled? Enter fullscreen mode Exit fullscreen mode This is where a docs-only API starts to feel thin. The integration does not fail because the endpoint is unknown. It fails because the lifecycle is not testable.…