This C library implements qTESLA, an efficient and simple signature scheme whose hardness is based on the Ring-Learning with Errors (R-LWE) problem and, hence, is conjectured to be secure against quantum computer attacks. The library, fully written in portable C, implements two different approaches for parameter generation: "heuristic qTESLA" that follows a heuristic parameter generation and is compact and efficient, and "provably-secure qTESLA" that follows a provably-secure parameter generation according to existing security reductions.