Why is this important?
Once you install Everdo, it's always awailable on you computer. As long as your computer boots, you can work. Internet connection is not required. You can even sync devices on your own using the Network Sync feature.
Web apps get acquired, closed, and changed for the worse all the time. A desktop-based app will continue to work unchanged for a long time, unless you chose to update it yourself.
To learn how Everdo stores data privately, see Everdo Data Privacy and Ownership