Rayyan is a free web-tool (Beta) designed to help researchers working on systematic reviews and other knowledge synthesis projects, and dramatically speeds up the process of screening and selecting studies.
From Rayyan Terms of Service
Where is data stored?
"Rayyan relies on cloud services like Heroku and Amazon Web Services to securely store its database, logs and uploaded files, to host and monitor the machines running Rayyan, and to send system emails. This Agreement is bound by the agreements of such services." For more information, visit https://rayyan.qcri.org/terms
What is the data backup policy?
"Automatic daily backups of the entire Rayyan database are stored on Amazon Web Services to ensure data durability, with a 1-month retention policy."