A few years ago, we ran a survey to see how people use FreeDOS. We found that people use FreeDOS in three different ways:
To play classic DOS games
You can play your favorite DOS games on FreeDOS. And there are a lot of great classic games to play: Wolfenstein 3D, Doom, Commander Keen, Rise of the Triad, Jill of the Jungle, Duke Nukem, and many others!To run legacy software
Need to recover data from an old business program? Or maybe you need to run a report from your old finance system? Just install your legacy software under FreeDOS, and you’ll be good to go!To develop embedded systems
Many embedded systems run on DOS, although modern systems may instead run on Linux. If you support an older embedded system, you might be running DOS. And FreeDOS can fit in very well.These days, I think that still represents most of the usage of FreeDOS. Although I'll admit fewer people probably develop embedded systems on FreeDOS. Much of the embedded systems market has shifted to Linux, where there's more developer interest. I think the Raspberry Pi and other low-cost and low-power devices have made Linux in embedded devices very attractive, so you don't see as much DOS in embedded systems today—but you do see some DOS sometimes.
Over the years, some developers have shared with me how they use FreeDOS to run an embedded system. My all-time favorite example is a developer who used FreeDOS to power a pinball machine. FreeDOS ran some application that controlled the board, tallied the score, and updated the back display. I don't know exactly how it was built. One way I can think to design such a system is to have every bumper register a “key” on a keyboard bus, and the application simply read from that input. I thought it was cool!
People sometimes forget about legacy software, but this pops up in unexpected places. I used to be campus CIO of a small university, and we once had a faculty member bring in some floppy disks with old research data on them. The data wasn't stored in plain text files, but as DOS application data. None of our modern systems would read the old data files, so we booted a spare PC with FreeDOS, downloaded a shareware DOS program that could read the application data, and exported the data to plain text.
There are other examples of legacy software running on DOS. My favorite is the McLaren F1 supercar can only be serviced with an ancient DOS laptop. And Game of Thrones author George R.R. Martin uses DOS to write his books. Those examples probably use MS-DOS, but there are likely a bunch of other legacy systems running from FreeDOS.
You can probably add a fourth category here: updating BIOS. I get a lot of email or other comments from people who still boot FreeDOS to update the BIOS in a computer system. DOS is still a safe way to do that.