Even though PieSync excels at syncing contacts in two directions, you can also configure Piesync to sync contacts in just one direction.
Syncing contacts in one direction gives you the benefit of making sure date only flows from App A to App B, but not from app B to App A. This is something you’ll likely want if you don't want data from another app to overwrite the app that you consider to be your source of truth. Syncing one-way is also the best option in case you just want to import and export data.
Setting your sync direction to one-way can be done at the top of your configuration screen. In between the logos of the two apps you are connecting, you’ll find a couple of arrows.
The arrow in the middle depicts a two-way sync and will be the default setting. The arrows on both sides depict a one-way sync in either direction.