Tink is a multi-language, cross-platform, open source library that provides cryptographic APIs that are secure, easy to use correctly, and hard(er) to misuse.

Tools to work with android .dex and java .class files

Project Wycheproof tests crypto libraries against known attacks.

Open-source XMPP client for Android

HiveMQ MQTT Client is an MQTT 5.0 and MQTT 3.1.1 compatible and feature-rich high-performance Java client library with different API flavours and backpressure support

mqtt-spy is an open source desktop & command line utility intended to help you with monitoring activity on MQTT topics