WeBWorK is a well-tested assessment system for delivering individualized problems over the web.

Whether as a student or instructor, I never really liked computerized tests.
But I had never heard about this FOSS project before. It is built on MathJax, and expanding into other STEM areas such as chemistry:

The [Open Problem Library] now includes problems from all ranges of mathematics, from pre-algebra through real analysis, as well as expanding into other STEM disciplines such as physics, chemistry and engineering.