Flux logo

Backend Developer

full-time Flux London

No. More. Paper. Receipts!

Were building the worlds first API to tell you exactly what youve bought, not just how much youve spent. We are looking for a talented developer with a passion for APIs and microservices who is excited at the opportunity to be involved with everything between feature planning, implementation, testing and architecture of a best in class system.

See our Life at Flux video to learn more about working at Flux: https://vimeo.com/302887685

Our engineering team are deeply curious and phenomenal problem solvers. We are building a revolutionary platform that is on the cutting edge of technology and financial regulation. As an engineering team we all work very closely with all parts of the business including legal, product, sales and operations. We don’t believe in working in silos and make sure people are mixed up, starting with where you physically sit at our headquarters in Old Street London. There is no dark corner just with engineers!


The projects that we work on:

  • Build out Blueberry, Fluxs merchant dashboard which processes complex analytics over large data sets in real time. This involves development of a GraphQL service that serves these stats and other data over websockets
  • Matching Algorithm, find and implement improvements to our matching algorithm that will allow throughput of millions of transactions per day
  • New product development (e.g. displaying nutritional info via receipts, building a better returns process for retailers or improving our developer experience)
  • Retailer and bank API integrations


The technologies we use:
Our tech stack follows open standards and handles a large volume of transactional data from some of the biggest retailers and banks in the UK. These are processed in microservices. Our backend is written in Kotlin which is based on the JVM and our frontend is primarily in React. We use GraphQL and subscriptions to facilitate real time communication between the frontend and backend and deliver analytics to our retailers in retailers. The infrastructure is built using Docker and Kubernetes.


We are looking for curious and passionate engineers who are are excited by Fluxs mission and product. We have no formal requirements, but ideally you should know some Java and have a strong desire to learn Kotlin. Experience of working in the start up environment and experience of building systems from scratch are both really interesting for us.


  • £50k to £80k plus equity
  • Generous holiday allowance (28 days) - we encourage everyone to use their allowance!
  • Company pension scheme
  • Weekly team lunches
  • Annual company trip
  • Work from home Fridays
  • Central London location between Shoreditch and Old Street
  • Unlimited artisan coffee
  • Fresh fruits, nuts, beers and other snacks provided
  • Latest Macbook Pro, screen and additional tech set-up required
  • Office building perks such as weekly yoga and fitness classes

https://tryflux.com/
published: Feb. 22, 2019

Apply for this position