Some of my course material is on GitHub, especially for courses that
are no longer running. Many courses have associated Maple code and
worksheets. Some also have interactive or three-dimensional diagrams
coded in Javascript.

This is a large project about holomorphic uniformisation of a family
of highly symmetric surfaces of genus two embedded in the 3-sphere.
There is a monograph of 160 pages together with about 20000 lines of
associated Maple code.

I have formalised proofs of various things in the Lean proof
assistant. There is a stand-alone repository which formalises proofs
from the paper "Iterated chromatic localisation" (written with Nicola
Bellumat), which should be fairly stable. There is also a general
library containing a wide range of different things under development;
this is neither stable nor well-organised. There is a fork of the
official Lean mathlib library, intended as a staging post for
contributions to that library.