Slim vs Symfony: What are the differences?
Developers describe Slim as "A PHP micro framework". Slim is easy to use for both beginners and professionals. Slim favors cleanliness over terseness and common cases over edge cases. Its interface is simple, intuitive, and extensively documented — both online and in the code itself. On the other hand, Symfony is detailed as "A PHP full-stack web framework". Symfony is written with speed and flexibility in mind. It allows developers to build better and easy to maintain websites with PHP. Symfony can be used to develop all kind of websites, from your personal blog to high traffic ones like Dailymotion or Yahoo! Answers.
Slim belongs to "Microframeworks (Backend)" category of the tech stack, while Symfony can be primarily classified under "Frameworks (Full Stack)".
"Microframework" is the primary reason why developers consider Slim over the competitors, whereas "Open source" was stated as the key factor in picking Symfony.
Slim and Symfony are both open source tools. It seems that Symfony with 21K GitHub stars and 6.98K forks on GitHub has more adoption than Slim with 9.92K GitHub stars and 1.84K GitHub forks.
Docplanner, Webedia, and eTobb are some of the popular companies that use Symfony, whereas Slim is used by Coderus, WebbyLab, and Die Coder GmbH. Symfony has a broader approval, being mentioned in 355 company stacks & 267 developers stacks; compared to Slim, which is listed in 26 company stacks and 19 developer stacks.