A friend of a friend just graduated from school and was having difficulty with software developer interviews. I put together this quick list from extensive research I've done about interview preparation.
It's a mix of resources: live interview practice; interview-type problems; and paid and free full-on algorithms and data-structures courses.
Pramp - Free, live interview prep.
Interviewing.io - Free, in beta, run by a woman with insight into the challenges of interviewing in tech, and especially if you're a member of an under-represented demographic - women, other minorities.
Gainlo - Paid. Live interview prep.
Interviewkickstart - Paid, but high quality, based on what I've read and my conversation with the guy who runs it. Bootcamp style interview prep.
In San Francisco? There's a meetup - Free. Live interview prep.
Coderust - Free. Coding problem practice. No interviews. Online judge.
Interviewcake - Paid. Coding problem practice. The most sophisticated solution hinting I've encountered anywhere.
Coursera Algorithms and Data Structures Specialization - Paid. Algorithms and data structures overview. Online judge.
Leetcode - Paid. Coding problem practice. online judge.
UVA - Free. Coding problem practice. online judge. Use the book Competitive Programming 3 to figure out which problems to solve.