SumUp Accelerator – Software Engineer Intern

Build real products that help millions of small businesses thrive.

At SumUp, we build fintech tools that empower over 4 million merchants across 37 markets to run and grow their businesses. The Warsaw Accelerator Program puts you at the heart of that mission - working on real product challenges in the Sell Online domain, from reducing merchant onboarding friction to building AI-powered tools that save merchants time and drive revenue.

This isn't a traditional internship. From day one, you'll join a small product team, take real ownership of a problem, and ship a working MVP alongside experienced engineers and product mentors. The top three performers will be offered a one-year contract at the end of the programme.

📍 Location: Warsaw, Hala Koszyki (office-first) ⏱ Duration: 3 months, 15th July – 15th October 2026 (full time) 💰 Salary: 8,000 PLN gross per month (Civil Law Contract / Umowa Zlecenie)

Curious what that actually looks like? Watch how our Accelerator participants become contributors to real-world features at SumUp.

What you'll work on

You'll join one of two teams tackling real merchant problems, including

Reducing onboarding friction by automating merchant setup and data import

Building smart waitlist and re-engagement tools to help merchants fill gaps and grow revenue

Exploring a consumer-facing marketplace where customers can discover and book services from SumUp merchants

Developing AI-powered tools - including a voice-based AI receptionist and a conversational merchant assistant

Your impact

Working alongside engineering mentors, product leads, and experienced SumUppers, you'll:

Design, build, and ship a functional MVP addressing a real merchant problem - from backend APIs to user-facing features

Write clean, testable, well-documented code and take part in code reviews from day one

Work in weekly sprint cycles, demoing progress every Friday and iterating fast

Grow your skills in Kotlin and TypeScript through a hands-on bootcamp in w