Whether you're looking for an alternative to expensive commercial software or just trying to get a feel for what's out there, AlternativeTo is a handy service for finding software alternatives.
AlternativeTo has hundreds of suggested alternatives in dozens of categories. You can narrow your search by licence type and platform making it easy to search for Mac-friendly commercial text editors or freeware Windows image viewers. Even if you're not looking for something specific you can check out the "Most Likes" category and see which alternatives are the most popular and might be worth taking for a test drive. For more ways to find alternative software check out our own list of superior alternatives to crappy Windows software.