Various aspects of the disclosure relate to automated route testing for application programming interfaces (APIs). An API route testing systems is configured to use classes and methods to identify API routes called by APIs and routes made available by application services. The class methods are customizable based on a programming language, testing or development framework, and the application type. Instances of classes are provided to detect routes similarly to API functions incorporated into a client application. Classes also detect routes in use by client services. A separate class is provided to compare the lists of API called routes and routes used by client services to return a listing of duplicate routes, unused API routes and client calls to invalid API routes (e.g., missing routes). For found duplicate routes and missing routes, the API route testing system generates an indication of the error and lists routes causing the error.