Stackshare is described as 'Learn about the tech stack behind some of the world's best software companies. See which tools and services they use, and how they're using them' and is an website in the education & reference category. There are more than 25 alternatives to Stackshare, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Android. The best alternative is AlternativeTo, which is free. Other great sites and apps similar to Stackshare are Product Hunt, Quora, Stack Exchange and Softpedia.
AlternativeTo let you find new Windows, Mac, Linux, online and mobile software based on applications you already know instead of useless categories. AlternativeTo is a new approach to finding good software.
Quora.com is a question/answer service allowing users to pose questions that other users can answer, each question and answer can have comments, each users can write one individual answer and there can be a summary answer.
Its main sections are Windows, Mac, Mac PPC, Linux, Games, Handheld (mobile software), Drivers, Mobile, Webscripts, and News. It also covers technology, science, health and entertainment topics from both external and in-house sources, and it provides software and game reviews.
When I am exploring alternatives to a product or service, I often to go Google, type "[product] vs ", and just see what it autocompletes. That usually tells me the most popular competitors. If I want to be thorough I'll do the same for the competitors, etc.