Benchmarks
The following benchmark suites have been used to evaluate Z3str4 and other string solvers.
Kaluza (legacy Z3-str archive)
IBM PISA (12 SMT-LIB instances, CVC4 version)
IBM AppScan (8 SMT-LIB instances, CVC4 version)
PyEx (in the SMT-LIB Reynolds collection; see the pyex/ entries)
The SMT-LIB versions of Kaluza and PyEx are also available in the QF_SLIA archive from the official SMT-LIB benchmark release.
Stringfuzz suites (external link)