We developed our own project called ESMira! Please have a look at:
https://github.com/KL-Psychological-Methodology/ESMira
This is a fork of the original PACO-project (https://github.com/google/paco).
It offers the same functionality but has a changed login-system. Participants are not bound to a google-account but can partake completely anonymous.
Also this project offers an alternative php-backend (instead of the PACO-Java-server) wich is optimized for needing view ressources and being easy to set up and has better ways of exporting datafiles.
This project is for researchers who need to offer their participants anonymity but only have the ressources of running a low end server with only standard-configurations.
If you have any suggestions found a bug or need any assistance in setting up the project feel free to contact me at jodliDev@gmail.com
LICENSE: Paco-Anon is licensed under the Apache 2.0 License