ykDroid is a free and open-source USB and NFC driver for Android, developed by Yussuf Khalil. Its main feature is to expose the challenge-response feature of YubiKeys, making it possible for other Android apps to use this feature.

This program is especially useful for those who use YubiKeys as a means of authentication on their devices. It enables YubiKeys to be used for authentication on other Android apps, making it more convenient for users who rely on YubiKeys for security purposes.

ykDroid is licensed as free software and the source code is available on Github. However, it is important to note that Yubico and YubiKey are registered trademarks of Yubico.