My programs are designed to help people in a sticky spot. For example, DDRescue-GUI helps users recover important data fast, using GNU ddrescue (GNU ddrescue's website), but without having to use the commandline, which can be a barrier to your average user. WxFixBoot fixes your Linux operating systems if they won't start, and allows you to configure your bootloader. These are advanced topics that are made accessible by the easy-to-use interface.
My open-source programs are written in Python, and they utilise wxPython, a cross-platform GUI toolkit that I chose because it works on all the major platforms (MacOS, Linux and Windows). Another reason wxPython is great is because it's easy to use, but very powerful at the same time. Being written in Python, these programs are naturally quite CPU and memory-efficient and will run even on very old systems without a hitch, which allows them to work quickly and efficiently. Despite being released a number of years ago, these programs are still actively maintained and tested with new distributions.
Since then, I have written my first commercial program, Disk Verifier. This tool can be used together with a disk erase tool (such as that included with Parted Magic for NIST 800-88-compliant disk erase verification. While commercial, Disk Verifier is still open-source like my other programs. I also made a PSID Unlocker GUI for Parted Magic to help with secure erasing SSDs, and I create tutorial and other informative videos for Parted Magic LLC.