Jof Arnold | Entrepreneur, engineer

Cofounder of—an IDE for building, deploying and debugging web service automations. Previous internet highlights includes cofounder and CEO of YC W11 FitFu, cofounder of dev agency BrainBakery and cofounder of Timecounts… each and every time with the awesome @Benjie. You can find me at @JofArnold on Twitter and on Linkedin and GitHub. I live in South East London with my girlfriend and a cat. I love cycling, although apart from the occasional KOM my enthusiam currently far exceeds my ability!

My career takes me from nuclear robotics and Russian spacecraft, through to motorsport and fuel injection systems and now web automations! If you’re interested here’s more about what I’ve been up to the past 18 years.


Before starting university, aged 17, I found a job working for Magnox PLC designing and developing software for robots to inspect and repair off-load nuclear reactors. It was just as great as it sounds; a teenage geek's dream come true.


After starting university - studying Mechanical Engineering MEng at Imperial College London - I managed to find myself working at Moscow Aviation Institute optimizing re-entry vehicle heat shields. In Russian. In Fortran 77. In DOS. None of which I understood at first. Somehow my professor seemed to be happy with the results however.

More Robots

Following MAI, I raised funding to visit Japan to pursue my love of robotics. Through broken Japanese and pure hustle I met with Toshio Fukuda (Nagoya University), Shuji Hashimoto (Waseda) and Yoshiuki Sankai - all of which are now legends. What amazes me is that even now the technology I saw there still seems futuristic.


Towards the end of my degree I shifted my attention to motorsport - designing and building aluminum and CFRP drivetrain components for the faculty’s racing car as well as acting as chief engineer for a small private racing team. After finishing university I had a chance meeting at Silverstone which in just a couple of weeks saw me raise funding to move to South Africa and work on optimizing a V8 sports car for a small startup.

Fuel Injection Systems

The motorsport projects were great fun, but eventually I had to accept a "proper" job working at Delphi Diesel systems designing high-pressure fuel injections systems. Operating at over 2,500x atmospheric pressure, these components are placed under exceptionally demanding stresses. I soon found I had a knack for balancing stress analysis, manufacturing, material science and testing and was promoted rapidly to lead engineer. My proudest moment was developing a disruptive new manufacturing process that improved fatigue life by 2x – something for which I received my first patent.

Internet Startups

After Delphi I started a small software agency with Benjie. At the time we didn’t know about things like VCs and Angels, so we structured our work to self-fund side projects. It was through the agency work we met and then joined BlogFriends - probably the first social news filtering startup. The app was built entirely within Facebook and attracted some of the most influential bloggers in the world.

After BlogFriends closed, we saw an opportunity with the then-new iPhone. Using the accelerometer we created a series of motion-sensing fitness apps called GymFu that trained people by counting reps. After some success plus funding from 4iP, Y Combinator and Start Fund we launched a new startup; FitFu. Despite selling over 250,000 copies and having a core of enthusiastic and dedicated users we decided to close the project in October 2012. Next time lucky!

Copyright Jonathan "Jof" Arnold 2017.