Senior Back-end Engineer

SumUp. A better way to get paid.

Job details

  • Full-time
  • map markerSofia, BG
  • cardRequires Work Permit
    Requires that you're a citizen or have a valid work permit / visa sponsorship to work in the country in which this position is based.
  • routeSenior
  • routeEnglish
    Preferred spoken language

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Our SumUp office in Sofia is hiring for the position of Backend Engineer.

In this role, you'll work with a small cross-functional co-located team to build tools that help hundreds of thousands of small businesses thrive. By shipping code early and often, you'll see the impact of your work on merchant's daily lives right away. You'll collaborate with experts in product, design, and operations to deliver mission-critical internal and external features that power the SumUp ecosystem.

We work on a number of different domains that span technologies, systems, and processes. A few of the technologies we're leveraging on SumUp platform include Ruby, Scala, Node, Erlang, Go, Kafka, Kubernetes and Docker.

Your role and responsibilities

  • Participate in API design and implementation for both internal APIs and those exposed to our third-party integrators.
  • Provide thoughtful and comprehensive documentation and testing for your features before shipping them.
  • Design, implement, and iteratively improve new backend services.
  • Maintain and extend existing backend services.
  • Collaborate with other software, QA and sysops engineers to ensure smooth deployment, continual operation and support for quality software.
  • Coach and mentor other engineers to increase their abilities and productivity.
  • Actively provide code review feedback to other software engineers, considering both style and implementation.

Main requirements

  • Experience with one or more of the following languages: Javascript on the Back (Node.js), Ruby (also on the Rails), Erlang/ Elixir, Java / Scala, Golang
  • Experience with microservices architecture and Restful APIs
  • Experience with Git
  • Experience with SQL (PostgreSQL)
  • Solid OOP and FP skills
  • Experience within Linux/Unix environment (comfortable working with a CLI)
  • Solid debugging, optimisation and problem-solving skills
  • Self-motivated, proactive and engaged attitude towards projects
  • Ability to write clear and concise code that your teammates can understand and build upon


  • Be part of one of world’s most exciting startups, on a mission to take over the world.
  • Responsibility and empowerment from day one.
  • Competitive compensation and education budget.
  • Participate in our weekly developer events, like Lunch & Learn and Hack Fridays.
  • We get together regularly for brunches, cocktail nights, football, yoga, massages and office parties.
  • At least one off-site every year, where the tech teams from Berlin, Sofia, and São Paulo gather to hack together. In the past we've gone to Germany, Bulgaria and Greece.
  • Three days of extra vacation +1 day added every year
  • Additional Health Insurance

Apply now

Sign up to apply

Or sign up to refer and earn a reward of €300