Wikipedia
AlternativeTo
AlternativeTo is a website which lists alternatives to web-based software, desktop computer software, and mobile apps, and sorts the alternatives by various criteria, including the number of registered users who have clicked the "Like" button for each of them on AlternativeTo.
Users can search the site to, for instance, find better alternatives to an application they are using or previously have used, or free alternatives, perhaps choosing a free web application ( cloud computing) which does not require any installation and can be accessed from any browser.