The M17 Protocol is currently supported on several software implementations
Hotspots
WPSD is a next-generation, digital voice software and dashboard suite by W0CHP, which includes native M17 support; as well as programs to update your modem firmware to the latest versions, which support M17.
Alessio IU5BON has a set of scripts to update the 'classic' Pi-Star to include M17. Note: This method uses outdated and unmaintained software.
Software Clients / Firmware
mvoice is the original M17 software client to implement the M17 Protocol and Codec 2, written for Linux.
mrefd is the first M17 Protocol reflector software, for linking M17 capable clients across the world
OpenRTX firmware for inexpensive DMR radios includes native support for the M17 Protocol
DroidStar is a multi-platform, multi-protocol DV client software that supports the M17 Protocol out-of-the-box, with no extra hardware or software vocoder needed.
MMDVM Jonathan G4KLX's Multi Mode Digital Voice Modem firmware for hardware digital voice includes M17 Protocol support.
MMDVM_HS Andy CA6JAU's MMDVM Hotspot firmware for DV hotspots (commonly used with Pi-Star) includes M17 Protocol support.
M17Client is a pure M17 Protocol implementation for MMDVM modems and hotspots which includes features like slow text during voice TX and GPS location information, written by Jonathan G4KLX for Linux.
Software Defined Radio Platforms
SDR++ includes an M17 decoder built in
OpenWebRX includes support for M17 decoding as an option either at build time, or in the software image