Backend Engineer | Ruby | Junior, Mid & Senior

Cleo AI Ltd

rubyonrails ruby London | Full-Time

See all Cleo AI Ltd jobs →

We’re looking for strong software engineers who want to work on a topic that matters to everyone: money.

Following a $10million Series A funding round, and as Cleo grows rapidly towards a million worldwide users, the problems we’re trying to solve get more complex. Budgeting, savings, and long-term money plans all require a smart, customer-centric approach to AI. That’s why we need you to join our fast scaling team.

What you’ll be doing:

Projects are undertaken over 2-week long sprints with sprint goals aligned to overall quarterly targets.

Some of our current interests lie in:

  • Machine learning: we have a wealth of user transaction data that we are leveraging, using ML techniques, to provide better insights to our users.
  • Scaling to a million users: we need to ensure that our tech stack can support our ambitious growth targets over the next 12 months. We are working on optimising our rails application for performance and memory usage, and scaling our database.
  • Product: working on a chatbot used by hundreds of thousands of people offers unique challenges and opportunities compared to your standard web application. We’re constantly iterating based on user feedback to provide the best experience to our users.

Our Stack:

  • Ruby on Rails
  • Minitest
  • Sidekiq
  • React
  • Postgres
  • Redis
  • Heroku
  • Github
  • CircleCI

About you:


  • are a Ruby developer 
  • can reduce complex problems to simple solutions consistently.
  • enjoy making those around you better engineers.
  • are excited by what we're building at Cleo; you are product-focused and care about making our users’ lives better.

Advantageous, but not essential;

  • Experience with React
  • Experience scaling platforms growing at pace (Postgres / Rails)

Our process:

  1. Quick phone call with a member of our engineering team to find out more about your experience and why you want to work at Cleo.
  2. Short take-home test.
  3. Onsite interview:
    1. Technical discussion with a senior engineer
    2. Pairing on an interesting problem
    3. Meet the CEO/COO


  • 25 days holiday a year. We want you fresh and fully charged.
  • Flexible working/ working from home when you need to.
  • Choose your own gear, ask for the tools you need, and we'll seek them out for you.
  • A lovely loft office, only a stone's throw from Old Street station.
  • Cleo socials and red-wine filled retros every week.
  • Fresh fruit deliveries, only the best coffee, and other snack-based perks.
  • Annual team offsite.
  • Weekly lunch-and-learns, as part of a general learning culture. Plenty of books on hand.

We are an equal opportunity employer and value diversity.

Salary range £40,000 — 110,000