XamPro

May I add to the list: qB (Question Bank Editor) - you can create your own Maths based exam papers in the style of an exam paper; filter types of questions by topic. Free to use (https://www.eflc.co.uk/qb)

One of the schools we work with uses Snipe-IT. They customized it to import staff and students directly from their MIS. I also understand that Snipe-IT supports SAML integration, enabling SSO and related features. It’s an excellent open-source solution—simple to set up and manage, and in my experience, it offers sufficient functionality for most schools.