Exercism was founded in 2013 by Katrina Owen as a way to practice programming through small, focused exercises. The platform stands out for two reasons: its extraordinary language coverage (over 65 languages, from Python and Go to Elm and Awk) and its human mentorship model where volunteer mentors review your solutions and provide feedback.
Each language track includes a series of exercises that gradually increase in difficulty. Learners download exercises, solve them locally in their preferred editor, and submit solutions through the Exercism CLI. The platform then runs automated tests and optionally routes the solution to a mentor for review. This feedback loop helps learners not just solve problems but write better, more idiomatic code.
Exercism is entirely free and open-source, run as a nonprofit and supported by donations and sponsors. The platform has attracted a dedicated community of volunteer mentors and track maintainers who create exercises, write test suites, and provide code reviews. Over 800,000 learners have used the platform to practice their skills.
In recent updates, Exercism added a browser-based editor so learners don’t need to install anything locally. They’ve also introduced concept exercises that teach language fundamentals alongside the practice exercises. For developers who already know one language and want to pick up another — or who want to deepen their understanding through deliberate practice — Exercism is one of the best resources out there.
