I wil present the open-source QSpace tensor library to treat non-abelian symmetries in tensor networks on a generic footing. With QSpace v1.0 initiated in 2006 on general abelian symmetries, akin to iTensor since 2008, it has progressed to general non-abelian symmetries with QSpace v2.* by 2012, then with SU(N) and Sp(2N) implemented. Major efficiency updates have been included in QSpace v3.*, aside with the implementation also of SO(n) and SO(2n+1). With QSpace closed source until now, QSpace v4.0 is finally going public. Based on its very history, QSpace has seen extensive scrutiny and testing in the past, by now with more than 75 research publications in a wide range of collaborations.