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SumUp

SMB-focused card payment processing hardware

Backend Engineer - Run & Grow

Backend EngineeringConfirmed live in the last 24 hours
Full-timeSofia, Bulgaria

About the Job

Requirements

  • Bring a strong backend engineering background in Go, or be a typed-language generalist ready to ramp up quickly.
  • Have designed APIs and distributed systems with clear contracts, versioning, and integration patterns.
  • Be fluent in relational and analytical databases, including PostgreSQL and Snowflake, and be comfortable selecting the right tool for each use case.
  • Have built Kafka-based, event-driven systems and understand event sourcing and change data capture (CDC) patterns.
  • Have experience in auditable, high-trust systems where every decision must be traceable, such as fintech, payments, or similar domains.
  • Have experience with testing, observability, and incident response practices, treating them as first-class concerns.
  • Take ownership of ambiguous problems and turn them into clear, scalable, and maintainable solutions.
  • Communicate clearly, collaborate effectively, and explain technical concepts and trade-offs to different audiences.
  • Value pragmatic engineering, continuous improvement, mentoring, and reliable production operations.

Responsibilities

  • Design, build, and operate production-grade backend services, application programming interfaces (APIs), and integrations, primarily using Go.
  • Build event-driven workflows and distributed systems using technologies such as Kafka and asynchronous processing.
  • Define clear service boundaries, data models, schemas, and API contracts that other teams can use confidently.
  • Build capabilities supporting merchant acquisition, identity, marketing technology, operations, risk, and compliance.
  • Own technical work end to end, from discovery and system design through implementation, testing, deployment, and production follow-up.
  • Modernise existing services and improve reliability through observability, security, failure handling, and incident response.
  • Collaborate with Product, Data, Operations, Compliance, Risk, Sales, Marketing, and other engineering teams to turn complex requirements into practical solutions.
  • Review code and designs, make pragmatic technical trade-offs, share knowledge, and mentor other engineers.

About the Company

SumUp

SMB-focused card payment processing hardware

SumUp provides card payment solutions for small and medium-sized businesses by selling portable card readers and handling the processing of credit and debit card payments. Its hardware plugs into( or connects to) mobile devices, enabling businesses to accept in-person card payments anywhere. Payments are processed through SumUp’s system with a flat 2.75% fee per in-person transaction, and there are no monthly costs or long-term contracts, making pricing simple and predictable. The company differentiates itself with transparent pricing, no contracts, and a globally available service across markets including the US, UK, Germany, France, and other regions, pairing affordable hardware with straightforward processing. SumUp’s goal is to help SMBs grow by giving them a secure, easy-to-use, and affordable way to take card payments anywhere.

Company size
1,001-5,000
Company stage
Debt Financing
Total funding
$4.1B
Headquarters
London, United Kingdom
Founded
2012

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