Wikipedia
FreeOTP
FreeOTP is a soft token authenticator that can be used for two-factor authentication. It provides implementations of HOTP and TOTP. Tokens can be added by scanning a QR code or by manually entering in the token configuration. FreeOTP can be used as a replacement for Google Authenticator even when logging into Google services. It is maintained by Red Hat under the Apache 2.0 license. It is available for Android and iOS.