Finding ways to advance your programming skills is easier when you find a good resource. If you're looking for a place to start, check out these sites that offer exercises and other challenges you can participate in. Some are individual and others competitions; many can be started any time, while others happen at specific times of the year.
-
Sites that offer challenges, such as 100 Days of Code or Hacktoberfest.
-
Sites that offer exercises/contests, such as Project Euler or Exercism.io.
-
Sites that offer exercises/contests, but who also work with companies to connect them with participants.
☝ (Note that these aren't a bad thing, and is probably a great way to monetize a site that has value for programmers too, but I'm placing them in their own area because they may be specifically what you're looking for... or trying to avoid!)
Have a site to add, or notice something that needs fixed? Contributions welcome!
Here's someone else's list: Lesser-known developer contests you can join in 2018