john-sierraI’m John (at right, on Netherlands TV)1. I’m a writer and app software engineer. I grew up in Southern California and I’ve worked in Northern California as a programmer and journalist.

I now live and work in London, where I operate a small consultancy, JupiterJazz.io, making native iOS and Android apps for clients. Recent projects have also led to working with technologies like BioPython as well as the cross-platform libraries React Native and Flutter.


My programming experience stretches back to my youth, during which I was obsessed with Commodore Amiga computers and earned extra credit from a kind math teacher after he discovered I had spent his trig lectures writing games on the class’s VAX mainframe about dudes with swords fighting wizards.

Lately I’ve been working the most with React Native and other modern JavaScript. I also do stuff with Unix, Web servers and databases.

I build, document and advise clients on how best to implement:

* Modern JavaScript applications (Node.js, React Native, etc.) and interactive features
* Phone apps (Swift, Objective-C), lately ones with swipey user-matching screens
* Databases (MongoDB, Firebase) for providing realtime info or syncing stuff between apps
* Friendly UIs for talking to creaky old data collections
* Custom software for radio hosts: paywalls, chat rooms, live Internet broadcasting

Podcast paywalls and software for podcast hosts

Tech portfolio here.


In between things I have written these books, as well as articles that have appeared in The New York Observer, The Guardian and other places.

Kearny’s Dragoons Out West: The Birth of the U.S. Cavalry (University of Oklahoma, 2016.) A piece of untold Western history, co-written with my dad!

Bad Moon Rising (PoliPoint Press, 2008.) This book is based on one of the first viral video scandals. (Journalists and researchers: Please see the FAQ).

Other Writing

Been working on some other writing projects, some of them interactive…and coming soon.


1 In 2016, my wife Mary and I accidentally ended up on an Amsterdam TV news crew’s feature about growing enthusiasm for Dutch track and field (at about 1:10).