ResellKit is a simple to use cross-listing app designed to increase your productivity, Start using ResellKit for FREE, No credit card required.
Cross-posting items have a cost. It's the time you spend to manage and track items on multiple platforms. The autopilot feature will look for new orders and removes sold items from the other platforms.
With this feature your chances to double-sell will significantly decrease, Note. Autopilot only works when RK is running and your device and is connected to the internet.
First list your inventory with your favorite platform. Once your listings are in that platform you can cross-list them to other two platforms in bulk. In the process you can review what will get published.
RK's documentation is a good place to start learning more about it and help you get started.