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(Senior) Backend Engineer (GoLang) - Online Payments

Sofia, Bulgaria · Engineering

SumUp’s Online Payments tribe enables merchants to offer state-of-the-art payment solutions for their online businesses. This tribe plays a key role in working towards SumUp’s vision of operating a 360° full cycle payments solution provider. Fundamental to the success of online payments is having a stable, responsive and adaptive Risk Platform. 

In the Risk squads we are building the anti-fraud mechanisms to help us keep our merchants and their customers safe. Monitoring million transactions per day and finding suspicious patterns between them is no easy task. That’s why we will be creating in-house solutions as well as integrating with third party anti-fraud providers. 

At SumUp you can be the hero who stops bad actors from operating and who enables small merchants around the world to accept payments in a safe environment!

You will be working alongside Software Engineers and Data Scientists that are creating an integrated fraud-prevention solution, that will take advantage of cutting edge technologies like machine learning and property graph databases. By shipping code early and often, you'll see the impact of your work on our merchants’ 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.

What you’ll do

  • Building backend services to automise fraud prevention and risk management in Online Payments

  • Maintain and extend existing backend services with a DevOps mindset (YBIYRI)

  • Collaborate with other Software, QA, Machine Learning and SysOps Engineers and Data Scientists to ensure smooth deployment, continual operation and support for quality software

  • Coach and mentor other engineers to further develop their professional and interpersonal skills

  • Actively provide code review feedback to other software engineers, considering both style and implementation

  • Provide thoughtful and comprehensive documentation and testing for your features before shipping them

You’ll be great for this position if

  • You have 3+ years' relevant engineering experience in financial services, risk, fraud prevention or related  in an agile large scale ecosystems and first-hand experience in mentoring.

  • You have vast experience with transaction processing systems that have high availability/throughput.

  • You have architectural awareness for systems that are dynamically evolving and are built to last  - microservices, messaging (Kafka is a plus), API design, DB solutions, networking, scalability, monitoring, logging.

  • You’re an ambassador for communication and collaboration, embracing trust and respect to actively shape a healthy team and feedback culture. 

  • You’re passionate about and/or experienced in Golang. Further experience in Java/Ruby/Python is considered a plus.

  • You have experience operating in a cloud environment, especially AWS.

  • You understand that sometimes there’s no need to reinvent the wheel. 

  • You have a DevOps mindset and a quality-first approach, and are familiar with engineering best practices to write clean quality code.


  • You’ll have the opportunity to build the foundations of our next generation Risk Platform.

  • You'll have the opportunity to make an impact as we work in flat hierarchies and with high autonomy.

  • You'll have the space to drive your career here and take ownership of projects.

  • You’ll be part of a diverse and international team.

  • You'll attend global offsites/hackathons/team events.

  • You'll receive competitive compensation and have access to an education budget.

  • You’ll receive 25 days paid vacation + 1 accumulative day for each year of employment at SumUp.

  • We offer additional health insurance, a subsidized Multisport card, free shuttle buses from Joliot-Curie metro station and other great benefits.

  • Innovative office design featuring an amazing 360 Sofia view, a music room, events forum space, fully equipped kitchen facilities; office relaxation activities such as yoga and massages.

  • Opportunity to work remotely from within Bulgaria, as long as you attend required in-person meetings, roughly once per month 

  • Home office policy (Totally remote at the moment due to Covid-19)

You are welcome to have a look at developer documentation for online payments integrations:

SumUp is also passionate about open source software, and we are proud of what we have given back to the community, including in GoLang.

Check out here:

About SumUp

We believe in the everyday hero. Those who have the courage to follow their passion and who have the strength and determination to realise their dreams.

Small business owners are at the heart of all we do, so we're creating powerful, easy-to-use financial solutions to help them run their businesses. With a founder’s mentality and a 'team-first’ attitude, our diverse teams across Europe, South America and the United States work together to ensure that small business owners can be successful doing what they love.SumUp is an Equal Employment Opportunity employer that proudly pursues and hires a diverse workforce. SumUp does not make hiring or employment decisions on the basis of race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by company policy. SumUp also strives for a healthy and safe workplace and strictly prohibits harassment of any kind.

SumUp will not accept unsolicited resumes from any source other than directly from a candidate. 

Want to get more insights about SumUp? Don't miss to visit us on our blog on Medium, or check our social media pages on Facebook, Twitter and LinkedIn.