Consfigurator
Lisp declarative configuration management system
Debian

Debian aims to be the universal operating system.
Policy
I am one of Debian’s two Policy Editors, responsible for defining and maintaining Debian’s formal technical framework.
dgit, tag2upload
Together with Ian Jackson, I lead Debian’s Git transition project. As part of this I co-maintain dgit, a bidirectional gateway between the Debian archive and Git, and tag2upload, a system to upload Debian packages simply by pushing a signed Git tag.
Package maintenance
I maintain or co-maintain our packaged versions of Steel Bank Common Lisp, git-annex, and fifty or so others.
I am a co-ordinator of the Common Lisp and Emacs packaging teams.
Emeritus
I previously served a term on the Technical Committee, Debian’s decision-making body of last resort; was a member of the archive administration team (”FTP team”); and co-maintained our packaged version of Emacs.
GNU Emacs

I am one of the head maintainers and a core developer for GNU Emacs, the ultimate text editor. I have also writen a few addon packages.
haskell-tab-indent
Minor mode for Haskell projects requiring tabs for indentation
org-d20
Minor mode for running tabletop roleplaying games that use a d20
transient-cycles
Define command variants with transient cycling
literate-scratch
Variant Lisp Interaction mode for easier interleaving of paragraphs of plain text with Lisp code
Perl distributions
papersway
PaperWM-like tiled, scrollable window management for Sway/i3wm
Git::Annex
Perl interface to git-annex
API::GitForge
Generic interface to APIs of sites like GitHub, GitLab etc.
Some other projects
hstow
POSIX.1 sh symlink manager, for configuration files in one’s home directory
sscan
Text UI for scanning with SANE
git-remote-gcrypt
PGP-encrypted git remotes
Unmaintained & historical
spwoutline
LaTeX class to export Org-mode outlines so that they still look like they do in an Emacs buffer
sariulclocks.cgi
Basic classroom management software I wrote while teaching English in Asia
jcrlaundry
Drupal 6 mobule written for Balliol JCR members to book time slots to use a machine in the laundry room