John Holdun

Software Portfolio

I’ve been writing software for a long time. Mostly on the web.

I’ve written a lot of words about software, too. I encourage you to explore my ideas about developing frontends, backends, healthy habits, and effective teams.

If you’re interested in my professional details, I have a résumé too.

ActivityPub to JSON Feed

Turns ActivityPub outboxes into reformatted JSON Feeds for your RSS reader, inspired by

Cooler Colors

Like a more pleasant less ad-covered version of coolors dot com.

When’s Good?

Like a more pleasant version of doodle dot com, just for fun but you can use it though.

Decision Cards

Pick something with your friends from a list. As soon as you all agree, it’s done, get out of there.


Notes on a work in progress: a hardware-agnostic MIDI step sequencer.


A zero-configuration Javascript library that adds a layer of smooth and fast in-page interaction to your web pages. All you have to do is add some hints to the HTML you already have. Conceived, designed, and produced as an employee at Postlight.

Train Approaching

A mobile-friendly web app I built for quick access to arrival times on the NYC subway. Add it to your home screen!


A personal web app for rotating my wardrobe and keeping my outfits fresh. Described as “like that thing in Clueless” by almost everyone who’s seen it.

Health Letters

Quick access to the health ratings for restaurants in your immediate area. Conceived as a proof of concept for a web app framework I never did much with; the data is locked in time, mid-2016.


A personalized list of new music releases every Friday, inspired by Rdio. I still miss Rdio.


A non-interactive Coffeescript port of the QBasic demo game GORILLAS.


A proof of concept for a real-time top-down MMO in the browser.


An interactive Twitter bot that pitted random words against each other. Created as part of a jam celebrating the finale of @everyword.


Upload HTML. There it is.


A searchable archive of every word that @everyword ever tweeted.


A stripped-down restyle of Google Reader.