+ [HBLink3](https://github.com/n0mjs710/hblink3) Open Source HomeBrew Repeater Proctol Client/Master, can be used to create links between hotspots and repeaters.
### Replacement Radio Firmwares and Reverse Engineering
+ [MD380Tools](https://github.com/travisgoodspeed/md380tools) and [TyMD380Tools](https://github.com/KG5RKI/TyMD380Tools) have reverse engineered the MD380 and MD-2017/MDUV380 series radios respectively and have tools to build and work with replacement firmwares. MD380tools has most of what you need to understand the TYT .rdt codeplug format.
+ [OpenGD77](https://github.com/rogerclarkmelbourne/OpenGD77) Firmware for DMR transceivers using the NXP MK22 MCU, AT1846S RF chip and HR-C6000 DMR chipset. Including the Radioddiy GD-77, Baofeng DM-1801 and Baofeng RD-5R.
+ [G90Tools](https://github.com/OpenHamradioFirmware/G90Tools) Tools and guides for working with the Xiegu G90 HF radio firmware
### Decoding
+ [multimon-ng](https://github.com/EliasOenal/multimon-ng) decodes many paging, AFSK modes, and similar, including POCSAG, FLEX, EAS.
+ [GNU Radio](https://github.com/gnuradio/gnuradio) a software development toolkit that provides signal processing blocks to implement software radios.
+ [PyMultimonAPRS](https://github.com/asdil12/pymultimonaprs) can take an RTLSDR or audio input and Igate APRS traffic.
+ [OpenWebRX](https://github.com/jketterl/openwebrx) Open source, multi-user SDR receiver software with a web interface, forked and improved from [HA7ILM's](https://github.com/ha7ilm/openwebrx) excellent initial project.
+ [Qradiolink](https://github.com/qradiolink/qradiolink) Multimode SDR transceiver for GNU radio
+ [Codec2](https://github.com/drowe67/codec2) is a FOSS ultra-low bitrate voice codec that's competitive from 3200 bits/s down to 450 bits/s. Also includes [FreeDV](https://freedv.org/), an HF digital voice mode. [PyCodec2](https://github.com/gregorias/pycodec2) is an easy Python wrapper.
+ [CSDR](https://github.com/ha7ilm/csdr) csdr is a command line tool to carry out DSP tasks for Software Defined Radio.
+ [editcp](https://github.com/DaleFarnsworth/codeplug/tree/master/editcp) a codeplug editor for the Tytera MD380 and MD390 as well as the Alinco DJ-MD40 radios.
+ [HPSDR](http://openhpsdr.org/) a hardware and software project intended as a "next generation" Software Defined Radio (SDR) for use by Radio Amateurs.
+ [SM1000 FreeDV adapter](http://www.rowetel.com/wordpress/?page_id=3902) FreeDV in hardware. Purchasable on [tindie](https://www.tindie.com/products/edwin/sm1000-freedv-adpapter/)
+ [Mobilinkd TNCs](https://github.com/mobilinkd) have open firmware, unsure if hardware is open. [Homepage](http://www.mobilinkd.com/)
+ [TR-9](https://github.com/sp5wwp/TR-9) implements an [M17](https://github.com/sp5wwp/M17_spec) (fully open source DMR/D*/P25 competitor) radio.
+ [QCX-SSB](https://github.com/threeme3/QCX-SSB) This is a simple and experimental modification that transforms your QCX into a (class-E driven) SSB transceiver.
+ [uBITx](https://www.hfsignals.com/index.php/ubitx/) An understandable general coverage HF SSB/CW transceiver kit