SPACER is an Android app developed by SPACER that allows users to lock and unlock spaces by using their smartphones. The app uses an electronic key that can be sent and received through the user's smartphone. With SPACER, users can easily and conveniently deliver and receive packages without the need for physical keys or face-to-face interactions.

The app is especially useful for those who need to deliver or receive packages but have conflicting schedules or are too far apart. Users can send an electronic key through the app to allow the recipient to access the package without actually meeting in person. This feature is particularly useful for e-commerce transactions or other situations that require close-range transactions.

In the future, SPACER aims to revolutionize the logistics industry by allowing users to collect their own packages during their daily commute or while traveling. The app is free to use and is available for download on the Google Play Store.