The era of web apps has come a long time ago and many excellent applications serve as constant inspiration: Figma, Excalidraw, Glyphr Studio, Fontra and many other interesting web applications.
Glyphs.app and the Abobe Illustrator had a great influence on my taste in working with fonts and outlines.
Ruby on Rails, Ruby and many great gems, Python and Flask — for backend. Vanilla Typescript, SkiaPathKit — for frontend.
Libraries for font generation and ML experiments: fonttools, ufoLib2, fontmake, PyTorch, HarfBuzz.
Huge thanks for curve math from legendary Pomax js library and book — A Primer on Bézier Curves. And many articles, and repos with Unicode, charsets, and computational graphics topics.