Load testing and cross-browser testing are ones of the web testing types particularly reliant on the support of cloud computing platforms for the implementation of TaaS. The main challenge involved in the composition of heterogeneous web application testing tools is the incompatibility of their inputs and outputs. However, the need to manually configure the tools greatly undermines the convenience and applicability of their applications. This paper proposes a system for the composition and delivery of heterogeneous web testing tools with the following contributions: (1) four adapters to automatically bridge the gap between the inputs and outputs of six state-of-the-art testing tools, (2) a composite web testing service with the adapters, and (3) two adapters to enable delivering the composite service via emails. Experiment results demonstrate the effectiveness of the proposed system in reducing the effort required for load testing and cross-browser testing by comparison with a conventional method.