Developed by Salvatore Sanfilippo aka antirez and licensed under the BSD 2 licence, kilo is a simple text editor in one file.
If you are learning C and want to see how to write a utility, this might be a good example to follow. Warning though he does use pointers so make sure you’ve learnt them first!
I had a stab at writing one quite a few years ago but it wasn’t very good. I have a suspicion that writing a good text editor depends upon you first creating a good implementation of the text storage. Solve that and it’s downhill for the rest.
I’ve added this to my curated library of C code, on the C Code link on the top menu.