Work with me

Please get in touch if you’d like to discuss working with me.

Skills and experience

Ways I can help

Past work

Here are a few examples of things I’ve worked on (not in chronological order).


I spent five years as Technical Director at Loco2, now known as Rail Europe. Our aim was to make it easy to book any European rail journey through a single website. I joined at an early stage, sat on the board, and played a key role in growing the business.

A big motivation for my involvement was the founders’ desire to use Loco2 to help mitigate climate change, by making it as easy as possible for people to take a train rather than a plane.

I worked on many things during my time there. Here are some that stand out:

  • Building up and guiding the technical team
  • Developing processes and documentation to keep the remote-first team running smoothly, such as: coding style guidelines, code reviews, on-call processes, error handling and deployment
  • Identifying and eliminating problem areas in the code base and infrastructure
  • Overhauling the ‘routing’ part of our software which identified which tickets were needed from which operator in order to make a complete journey
  • Developing our software architecture so that we were able to easily plug in new rail operators when we formed a commercial agreement with them
  • Reworking our hosting infrastructure to be more resilient and maintainable

Jamie Andrews – Co-founder and former CEO:

I first worked with Jon back in 2007 when we were both at Torchbox, and I was immediately impressed at how capable and confident he was despite being so young. When I started Loco2, Jon was the obvious choice to lead the technical work. I eventually persuaded him to become technical co-founder and CTO when he graduated from Oxford in 2011.

Over the next five years Jon did amazing things, from building outstanding software to designing and evolving our technical infrastructure as we grew substantially. It’s impossible to overstate Jon’s positive impact on the inception and functioning of the organisation as a whole. He brought a ruthless efficiency to decision-making and ensured that we consciously designed and questioned processes, whilst all the time safeguarding the agile, lean mindset that is at the heart of his professional philosophy. I learned a huge amount from him and it would be a pleasure to work with him again in future.

Jon would thrive at the heart of a small, highly capable team with a delivery-focused mindset. Equally I’m sure he would bring a lot to larger teams, provided he is given the agency to make positive changes. He has the patience and written communication skills to clearly outline the next steps he intends to take when tackling a problem, and is never afraid to be honest when challenges are larger or more complex than initially envisaged. This honesty and diligence, when combined with Jon’s obvious technical flair, makes for a highly effective skillset that is incredibly difficult to find.


I worked with British startup Dizzie (formerly known as Good Club), to advance their mission to eliminate waste packaging from everyday grocery shopping. The service made it easy to buy kitchen staples and have them delivered to your door in returnable, reusable packaging that would then go back to the Dizzie warehouse to be refilled.

While the business has now refocused on offering its technology and expertise to other established retailers, during my time there I worked extensively on the custom-built application that facilitated customer orders and managed the extensive warehouse logistics required by the reusable packaging model.

The application was built with the modern functional programming language Elixir and its web framework Phoenix, with interactivity enabled by Stimulus and later Phoenix LiveView.

Towards the end of my time at Dizzie, I took the role of interim CTO and oversaw the technical side of a full rebrand of the business.

Danny Blackman – Co-founder:

Jon is hands down one of the most impressive engineers I’ve had the pleasure of working with. Over 2 years together at Dizzie, Jon made a huge impact on the product and codebase, the engineering team, and our process.

Working remotely from the other side of the world in opposite timezones was only made possible by Jon’s excellent communication skills and thorough and pragmatic approach. I was always very happy to brief him on work knowing that he would approach it in a thoughtful and intelligent way, without the need for much oversight. He always delivers excellent work without fail, and when our CTO stepped aside, Jon was the obvious choice to step into the role.

He would be an asset to any engineering team and I would work with Jon again in a heartbeat given the chance.


When I first came to Australia I worked at the new ‘digital bank’ Up. I learned lots of new things on this project, such as React Native, GraphQL, Relay and Flow.

One significant contribution I made was around the automated testing infrastructure. I discovered that end-to-end testing of mobile apps is very difficult to make reliable—our builds were often failing due to flakey tests. After working to find and solve various individual cases, I saw an opportunity to rewrite our testing code to avoid common problems and be easier to use. Completing this work resulted in a step-change in build speed and reliability.

Michael Morris – Head of Technology:

Jon Leighton is an amazing developer. Jon’s breadth of experience and critical thinking ability make him capable of solving any problem (code or otherwise) he sets his mind to. Jon was an inspiration to our team through his ability to lead by example in terms of communication (eg commit messages) and also to contribute to other areas of our company. My standard for an engineer is, if assembling a team again, would I have a place for them? - In Jon’s case - absolutely.


I helped the team at YourGrocer improve their technology platform in response to a growing customer base:

  • Fixing performance problems
  • Upgrading important components of the system, including a major Rails upgrade
  • Improving automated testing infrastructure to make it easier to deploy new changes with confidence
  • Understanding and documenting the pros and cons of the current architecture, and how it could evolve in the future

Morgan Ranieri – CEO:

Jon is a great developer, clear thinker and effective communicator. He joined our team for a 4-month contract and was able to hit the ground running very quickly. I was impressed at his ability to understand the team’s priorities, wrap his head around our setup and start making an impact. Jon was confident in forming coherent solutions and able to communicate them well with tech and non-tech folks. He also left us with some of the most accessible documentation I’ve come across - thanks Jon!

Open source

I used to be very active in open source software development in the Ruby community.

  • I was part of the Ruby on Rails core team, and did a lot of work refactoring and improving the database layer, Active Record
  • I started a project called Poltergeist, which enables developers to use PhantomJS to perform end-to-end testing of web applications
  • I started a project called Spring which speeds up development of Rails applications by keeping them running in the background. Spring is now included in new Rails applications by default


I have a BA in Computer Science from Oxford University.


I used to give talks at technical events, before making a decision to step away from it.

Here’s a non-exhaustive list: