From the description: "Pick from an expanding library of more than 150 questions, code and submit your solution to see if you have solved it correctly" the Project Euler site tops that number with a similar proposition. Project Euler has almost 500 problems at https://projecteuler.net/.

OK, perhaps it is more targeted to the mathematically inclined, instead towards engineers on their route to a technical coding interview. Nevertheless it has a very interesting set of (challenging) problems, and I see a number of similar problems at LeetCode.

Project Euler is also a great environment for trying out new programming languages, as the code is not part of the submission. As long as you come up with the correct answer (which is always a number), Project Euler considers it solved. You might solve the problem with C, Python, ACL, Ruby, pen-and-paper, Ada, Mathematica, Wikipedia... Euler doesn't care. So, sometimes I solve some problems multiple times, just to try different concepts or algorithms in other languages.

(By the way, the title "Software engineering interview questions" is a little broad. It is a set of (mainly mathematical) problems that may be solved by writing some code, but it doesn't address other relevant software engineering experience/aspects.)