For category theory in particular
- Guide to commutative diagrams packages (J.S. Milne 2005)
- diagrams.tex (Paul Taylor 1986 –), classic macros: highly rated for drawing simple or very complicated commutative diagrams for category theory.
Packages for drawing diagrams more generally
- pgf and TikZ (Till Tantau 2005-: a general TeX macro package for generating graphics, with a user-friendly syntax layer called TikZ).
- XY-pic (Kristoffer Rose and Ross Moore 1991 – 2002; extremely powerful and versatile: there’s a chapter on this in The LaTeX Graphics Companion)
- Tree drawing in LaTeX (from LaTeX for Linguists)
- The semantics package supplies T-diagrams and other resources.
- Dednat (Eduardo Ochs, 2008) preprocesses proofs or diagrams written without markup.