Unfortunately, most of my projects are not (currently) open-source, but some of the more interesting open-source projects I’ve meaningfully contributed to in the past include:

• Factor, a modern postfix language (think a high-level, new take on Forth);
• Mercurial, “the other DVCS”, which is unfortunately so amazingly dead that both Facebook and Google are busily adopting it as their One True SCM even as we speak; and
• Miniredis, a pure-Python Redis-compatible server I wrote a decade ago to provide a Redis workalike that could operate on Windows

If you insist on something recent, hayom is a simple plaintext journaling tool I’ve been working on when I have that rare moment of spare time.

You can see a full list of everything I’m actively working on in my by visiting my sourcehut account.

On the closed-source front, the biggest project I worked on in the past was at Fog Creek, where I worked heavily on Kiln, a cutting-edge DVCS hosting solution initially based on Mercurial, and later allowing each member of a team to make their own choice between Mercurial and Git on a commit-by-commit basis—the only tool to provide such functionality. Way back at the beginning of my career, I worked on Fog Creek Copilot, a remote assistance solution for micro-ISVs.