Abstract This package provides test suites for the C-DTLZ problems (Jain & Deb, 2014), a constrained version of the DTLZ problems (Deb et al., 2001). The DTLZ problems are a set of continuous multi-objective optimization problems consisting of seven types, each supporting a variable number of objectives and variables. The C-DTLZ problems extend the DTLZ problems by adding various types of constraints to some of them. The objective functions are wrapped from the DTLZ test suite in optproblems, while the constraint components are implemented separately according to the original paper (Jain & Deb, 2014).