The realisation of Service-Oriented Architecture (SOA) to communicate data between systems running on different platforms lack an organised framework to capture the essential elements required for successful interoperability between web applications and their services. In this work, a SOA for Data Interoperability in Web Applications (SOADIWA) was designed. The architecture of SOADIWA was based on five layers, namely Web Application Layer (WAL), Quality of Service Assurance Certifier Layer (QoSACL), Web Service Layer (WSL), Visualization Input Layer (VIL) and Visualization Output Layer (VOL). In WAL, the Service Requester (SR) initiates a request for data from the Service Provider (SP) through the QoSACL to provide appropriate website via WSL for rendering of services which must be accepted, processed and returned for a particular need in VIL. The requested data is filtered in VIL for data exploration and analysis in VOL using context-sensitive visualization techniques. The purpose of QoSACL is to check and verify the claims made by the SP about its quality of service. This enabled the SR to choose the service that satisfied its needs. The implementation comprised of Java Script, Microsoft Visual Studio 2017 and NuGet packages; while the experiment was simulated on LoadUI pro application. Standard metrics such as Optimal Performance (OP) and Phased Effort Distribution (PED) were developed to test SOADIWA. These results conformed to basic web service interoperability. The work led to the integration of a host of techniques towards the creation of a novel tool that is useful in web domain using SOA approach.