Senior Backend Engineer - Commercial Systems and Intelligence Cologne, Germany

Senior Backend Engineer - Commercial Systems and Intelligence Cologne, Germany
· Engineering

About the team:

The Commercial Systems and Intelligence squad is a newly formed team within Sum Up's Acquisition Mission under the Run & Grow tribe. We sit at the intersection of data, backend engineering, and sales operations, building the infrastructure that powers how Sum Up attributes merchant acquisition, calculates commissions, and understands the full lifecycle of every merchant.

Today, these processes are largely manual. We're here to change that, automating what's opaque, and building systems that sales representatives, leadership, and analysts can actually trust. You'll join at the very beginning, helping to shape how the squad works, the architecture it builds on, and the standards it holds itself to.

What you’ll do:

Aggregating data from across the Sum Up ecosystem to determine which acquisition channel or sales agent drove a merchant to take a valuable action (e.g. signing up, adopting a product)

Establishing data models, API contracts, and rule definitions that automate existing manual commission workflows for field and tele-sales agents, partnerships and merchant referrals

Build the Lifecycle Event Log in close collaboration with the Merchant Intelligence squad. A centralized store of curated merchant lifecycle events (signups, product usage, verification, purchases) used across attribution, recommendations, customer support and sales

Build internal back offices and APIs for sales representatives and leaders to monitor commission and modify commission plans, manage portfolios and resolve disputes

Define and document API contracts, schemas, and integration patterns that other engineering teams can adopt confidently

Establish best practices for testing, observability, and incident response within a newly formed squad

Use AI and agentic coding tools deliberately, to scaffold services, write tests, explore unfamiliar code, and draft documentation while maintaining full accountability for what gets shipped

You’ll be great for this role if you:

Bring a strong backend engineering background in Go, or are a typed-language generalist ready to ramp up quickly

Have designed APIs and distributed systems with clear contracts, versioning, and integration patterns

Are fluent in relational and analytical databases (PostgreSQL, Snowflake) and comfortable making the right choice for the right use case

Have built Kafka-based, event-driven systems and understand event sourcing and CDC patterns

Have experience in auditable, high-trust systems where every decision must be traceable — fintech, payments, or similar domains

Have built services from scratch in greenfield, early-stage squads with limited prior context, and are energized, not unsettled, by that challenge

Have experience with testing, observability, and incident response practices and treat them as first-class concerns, not afterthoughts

Are resourceful and adaptable, you take end-to-end ownership, do more with less, and adjust quickly as priorities shift

Can bridge technical and non-technical audiences, translating fuzzy problems into clear engineering work and explaining trade-offs to engineers and sales stakeholders alike

Are pragmatic, you know when good enough ships value and when something genuinely needs to be done properly

Have mentorship instincts, you raise the bar for the people around you, not just your own output

Why you should join Sum Up:

Opportunity to work with Sum Uppers globally on large-scale fintech products used by millions of businesses worldwide, from our Berlin office. This involves an office-first setup

Commitment to Diversity and Inclusion:
Be part of a workplace that values and promotes diversity, fostering an inclusive environment…