1. Z3str2 String constraint solver.
https://sites.google.com/site/z3strsolver/
2. IBM security AppScan source.
http://www-03.ibm.com/software/products/en/appscan-source
3. Kausler suite.
https://github.com/BoiseState/string-constraint-solvers
4. LibStranger.
https://github.com/vlab-cs-ucsb/LibStranger
5. Personal communications with the stranger team (2015)