There are a few different “flavours” of software available to amateurs.
DV4 Mini users (http://xreflector.net/Download/DV4mini/inhalt.html)
The DV4 Mini has been around a fair amount of time however, the ability to purchase the dongle has become a lot harder however, here are still many of them in use.
Raspberry Pi – http://xreflector.net/Download/DV4mini/Raspberry/inhalt.html
David PA7LIM, has been working on this as a hobby project which is a simple bit of software that works very well and has over time, expanded to support numerous platforms. BlueDV supports DMR, D-Star and YSF. It’s user interface is neatly set out, there is a basic setup page and the ability to automotically download database updates. After choosing the relevant software link below, the page will also give you various bits of information.
Note, that the software differs depending on the operating system. It seems that the Windows version is about the most up to date version.
Android – https://www.pa7lim.nl/bluedv-android/
Windows – https://www.pa7lim.nl/bluedv-windows/
AMBE3000 – https://www.pa7lim.nl/ambepage/
Pi-Star has become very popular with hotspot users and is also used by repeater keepers for MMDVM based repeaters (which are a lot cheaper than commercial repeaters). The software supports DMR, D-Star, YSF, NXDN and P25. It can also work cross mode – YSF2DMR, YSF2NXDN, YSF2P25, DMR2NXDN & DMR2YSF.
DMR users can also access Brandmeister, Phoenix & other DMR networks without the need to change any settings within the software by utilising DMR Gateway – the same is utilised on some repeaters in order to give DMR users access to both networks via one repeater. The system assigns a prefix to each network which is then used as the prefix for the talk groups relevant to that network so that the software knows which network to route your activity through. More information via https://f5vmr.wordpress.com/2020/02/04/today-on-dmr-configuring-the-dmr-gateway-function/ as well as the official Pi-Star online forum – https://forum.pistar.uk/
Toshen KE0FHS wrote a guide on how to use pi-star which I have used a few times, especially to setup the wifi access without needing to use a LAN cable, through a system called Auto Access Point (Auto AP) – https://amateurradionotes.com/pi-star.htm – If you look on the Pi-Star website there is a Wifi Builder option which creates a file which you need to copy to the micro SD card whilst it’s still in your computer – this will contain a single WiFi connection and once your hotspot is working, you can then go into the Pi-Star Configuration file and add more WiFi connections – https://www.pistar.uk/wifi_builder.php
There is also a pi-star users support group – https://groups.io/g/PiStar
Raspberry Pi – https://www.pistar.uk/downloads/
Another project by David PA7LIM. This is not a hotspot software but can be on numerous devices to access various digital modes such as DMR without the use of a radio. It supports Android (4.x or higher) and Windows 10. This can also be used on numerous Network Radios.