PACT is an open source tool. It helps in testing the interactions between consumers and service providers. However, it is not included in the contract, increasing the reliability of the application. The consumer service developer starts by writing a test which defines a mode of interaction with the service provider. The test includes the provider’s state, the request body, and the response that is expected. Based on this, PACT creates a stub against which the test is executed. The output is stored in a JSON file.