Here is my list:

- A server package containing: web server, smtp server, database engine, page generating language and a supervisor that keeps everything alive. All written in C and I use them for all server programming I do.

- A file renamer that can rename multiple files. It puts the filenames in a text file and lets you edit it and then renames the files according to the changes.

- A RISC-V start kit containing a very simple assembler, disassembler and documentation.

- A script that runs twice a day and downloads things from the internet (like weather forecasts, news feeds, podcast feeds, train traffic info), puts them in a folder and does some processing and formatting. Then I can easily go through it all to get my daily information.

I write a lot of code just for myself, with no one else ever using it.

An expense tracker. An analytics system for my mobile game. A Telegram bot that helps automate some things. A digital clock made on ESP32. A notification service that calls me with Twilio when some other events happen that need my immediate attention. A deployment automation system that replaces Cloud Run for me – well, this one I vibe coded, not actually wrote myself, but I believe it counts too.

Writing code for myself is the second best after writing code for someone else!