I have an e-commerce store and a website of my store. But now I want to create web app for my store. I want my web app secure and user friendly across all browsers and devices. I want an application testing who could verify all the functional requirements and deliver a product that satisfy us. I need to contact to a website who could provide me testing services. But I don't know which website is better for these services. If anyone have suggestion then kindly share with me. Thanks