Testing is one of the critical processes in software development life cycle. It plays key role in the success of software product by improving its quality. Web-based applications are emerging and evolving rapidly; their importance and complexity is also increasing. Heterogeneous and diverse nature of distributed components, applications; along with their multi-platform support and cooperativeness make these applications more complex and swiftly increasing in their size. Quality assurance of these applications is becoming more crucial and important; testing is one of the key processes to achieve and ensure the quality of these software or Web-based products. There are many testing challenges involved in Web-based applications. But most importantly interoperability and integration are the most critical testing challenges associated with Web-based applications. There are number of challenging factors involved in both integration and interoperability testing efforts. These integration and interoperability factors have almost 70 percent to 80 percent impact on overall quality of Web-based applications. In software industry different kind of testing approaches are used by practitioners to solve the issues associated with integration and interoperability, which are due to ever increasing complexities of Web-based applications. It is fact that both integration and interoperability are inter-related and it is very helpful to cover all the possible issues of interoperability testing that will reduce the integration testing effort. It will be more beneficial if a dedicated testing team is placed to perform the both integration and interoperability testing.