Mariusz Sołtysiak is a Staff Software Engineer with over 15 years of hands-on experience building and evolving backend systems, currently driving architecture, reliability, and best practices at SumUp from Lodz, Poland. He blends pragmatic craftsmanship with a strong focus on observability, extensibility and event-driven design, having led migrations to Java/Kotlin, PostgreSQL, Kafka, gRPC and Kubernetes. Beyond coding, he shapes hiring, mentoring, and cross-team knowledge sharing—regularly bringing Kotlin expertise into PHP-oriented squads and running initiatives like risk assessment and event storming. Comfortable as both a technical leader and a bridge to the business, he has a track record of refactoring legacy systems into maintainable modular platforms. An early freelancer and full-stack developer, he keeps a practical, product-oriented lens on engineering trade-offs.
11 years of coding experience
16 years of employment as a software developer
Master of Engineering - MEng, Information Technology, Master of Engineering - MEng, Information Technology at Wroclaw University of Science and Technology
PHP SDK for Bonanza Marketplace and its "Bonapitit" REST API.
Contributions:5 releases, 35 commits, 2 PRs in 10 months
apimarketplacephpsdkpayment
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Mariusz Sołtysiak - Staff Software Engineer at SumUp