In May 2009, after some weeks of programming, my brother and I published the first version of TeXercises. As a teacher, you prepare around 50 exams a year - this alone results in several hundred exercises. I did the maths right from the start: Having a database for exercises and collections (that includes exams) will save you A LOT of time over the years.
After saving every exercise in separate .tex-file, collecting them in another .tex-file and building a .pdf from yet another .tex-layout-file in the beginning, I soon realized there needs to be a database solution. The decision to make it public was mainly driven by the wish to have the solutions available for the students anywhere 24/7.
Since this "TeXercises 1.0" always did the job for me, I never improved it. Until Corona came around the corner. Suddenly the urge to improve the database grew stronger - and I finally found the time, because all other activities were forced to zero.
That's the reason "TeXercises 2.0" is now live. Meanwhile, some of my own former students are teachers for physics or maths and they collaborate with me. And we are looking for even more motivated teachers to contribute to the database. Just contact us.