Your trees can be made available to just qualified individuals, either by implementing IP Filtering (using the Settings tool).
We run on Amazon RDS and Elastic Beanstalk. As a part of our SLA, the Zingtree databases are backed up daily.
Our server uses PHP. We sanitize all variables before using them in database reads and writes.
Amazon is fully ISO certified. Details here.
Snapshotting and Local Backups
Each time you make a change to a change a tree, a "snapshot" is created. You can recover any snapshot from More Tools, Snapshots.
Within your organization, tree Admins can grant or revoke Admin, Edit or View access to trees for collaboration.
Other Security Measures
We run security checks with Qualys, and ensure that there are no database holes. Logins are protected by SSL. In addition, when you create an account, we give you feedback about password strength. Of course, your account is only as secure as the passwords you use.