Due to their heavy reliance on server infrastructure, the current computation-intensive SaaS suffer from scalability issues compared to the existing data-intensive commercial SaaS. Offloading certain computations to the client browser can resolve these scalability issues but the current Browser APIs are complex to use and integrate in a single software. We propose in this paper four high level APIs that harness existing browser-based paradigms and proven software architectures to reduce the complexity of parallel computing and device-agnostic interactive rendering in the web browser. To allow experimental results, we have developed a proof-of-concept browser-based and interactive diffusion MRI where we have particularly deployed a parallel Diffusion Tensor Estimation. Our platform provides us easy APIs achieving up to 4 times speedup in parallel computation and real-time interactive rendering performances across different Browsers and Devices in comparison to other existing solutions in the Diffusion MRI Community.