LeetCode

Although it is intended for people with some programming knowledge, LeetCode is an excellent resource for developers looking to prepare for interviews or gain attention from top tech companies. It’s even used by top companies like Google, Facebook, Microsoft, and Amazon to gauge the talent of their interviewees.

This platform has over 2,000 projects in 14 programming languages and offers weekly and monthly challenges for everything from algorithms and system design to database and functional programming. They also collaborate with companies to provide assessment and training tools to help programmers develop, as well as interview preparation tools to help top candidates get jobs. LeetCode offers a variety of services such as practice interviews, contests, and, most significantly, coding problems.

LeetCode now hosts over 2,500 interview questions and is constantly adding new problems. LeetCode has grown in popularity to the level that companies use it to source interview questions. That's right, if you practice on LeetCode, you'll be significantly more likely to see those exact questions in your interview. LeetCode includes a simple in-browser code editor. There is no need for a development environment; simply write your code and execute it.

Website: leetcode.com