Best website for testing APPs and Websites

We use BrowserStack to test how our website looks in different devices and we can make changes accordingly, this helps us to save a lot of revenue as we don't have to purchase multiple devices and check and all we can do it is check everything in a single place, thereby we can use this revenue to invest for other purposes.

Challenges like we have to purchase the physical devices to check everything live, which was really costly and also not worthy, because we cannot sold back old electronic gadgets at a profitable price and also the gadget becomes unusable after our testing is done, even if we manage to find someone who have the old device, still we have to pay them to test our website and give us a feedback.