Systems, methods, and software can be used to automate software verifications. In some aspects, one or more application program interface (API) call pairs are generated based on a source code of a user module that invokes an API. Each of the one or more API call pairs comprises a first API call that invokes the API followed by a second API call that invokes the API. One or more fragments are generated based on the one or more API calls pairs. Each of the one or more fragments represents an execution sequence that includes at least one of the one or more API call pairs. The one or more fragments are verified.