freeCodeCamp

freeCodeCamp is a nonprofit and a huge community that teaches people around the world to code completely for free. It's backed by thousands of volunteers and donors, not a profit-driven company, so the entire curriculum is and stays free. It suits absolute beginners who have never written a line of code, as well as more advanced learners who want to fill in a specific skill.

Learning happens right in your browser: you read a short task, immediately write code in an interactive editor, and the platform instantly checks whether the challenge passed. You move through thousands of small challenges grouped into coherent blocks and build real projects along the way. After completing a section's required projects, you earn a certificate you can add to LinkedIn or your CV.