Payment Solution Engineer

Location: Belgrade Workplace: onsite About Unlimit   Unlimit is a global fintech ecosystem built to eliminate financial borders holding businesses back. The company provides the extensive infrastructure needed to scale globally, integrating payment processing, multi-currency business accounts, BaaS and crypto gateways into a single, intelligent platform.   Across 17 offices globally, Unlimit bridges hyper-local expertise with a high-capacity financial network, giving companies the agility to expand across regions with operational confidence and speed. Driving the evolution of payments, Unlimit is transforming its infrastructure from human-operated fintech into AI-native financial infrastructure — where APIs are consumed by machines, integrations are negotiated by agents, and systems evolve continuously through intelligent automation. Our next users are not only humans. They are AI agents acting on behalf of humans and businesses.   Unlimit serves more than the needs of businesses today; we are building the nervous system for a borderless global economy. As Unlimit expands into new markets, each license we obtain connects us to that country's banking infrastructure — domestic clearing and direct interaction with other participants in the banking system. This role owns the integrations that bring those rails live: working hands-on with central banks, national clearing systems, and third-party BaaS providers.   You'll act as both project lead and solution engineer — running each integration with the regulator or provider and doing the technical implementation yourself. It's a role that sits between delivery and architecture: you own a project end to end while staying deep in the technical detail. What You'll Be Doing Own central bank and clearing integration projects end to end, from kickoff to go-live, as Unlimit enters new licensed markets. Act as the primary technical and project contact for regulators and their assigned counterparts. Manage the full onboarding path: credentials and environment setup, certification test cases, and production activation. Set and defend realistic launch timelines, and keep projects on track within their delivery window. Design and implement the connections that plug Unlimit into local clearing and payment systems. Deliver integrations with third-party BaaS providers to bring additional payment rails online. Document integrations and hand over clean, maintainable solutions to engineering and operations. Our Tech Stack You'll work across a stack that includes: Backend & tooling: JVM, Kotlin, Java, Spring Boot, Modulith, Javalin, jOOQ, Temporal Integration & messaging: REST and SOAP/XML web services, ISO 20022; Kafka and SQS/SNS for internal eventing Security: mTLS, PKI, certificate-based authentication, and digital signatures — standard for central bank and clearing connections Cloud & infrastructure: AWS, Docker, Kubernetes, Terraform, GitLab CI/CD What We're Looking For 5+ years in payments, banking, or integration engineering, with hands-on ownership of complex integration projects. Direct experience integrating with central banks and/or national clearing and settlement systems. Hands-on familiarity with payment schemes and networks such as SWIFT and SEPA. Strong understanding of payment rails, clearing, and settlement flows. Comfort with payment messaging standards and integration patterns (ISO 20022, MT/MX, SOAP/REST web services, certificate-based auth). The ability to run a regulated project independently — managing scope, timelines, and regulator communication without close supervision. A solid awareness of AI-driven engineering practices and where the tooling is heading. Hands-on experience putting AI tools to work — LLMs, AI-assisted development environments, and automation frameworks — to sharpen productivity, system performance, or technical decision-making. A clear, structured communicator who can hold their own with regulators and technical counterparties alike. Nice to Have Experience working directly with financial regulators, especially in Europe, Mexico, and Brazil. Familiarity with local schemes such as SEPA (Europe), SPEI (Mexico), and Pix (Brazil). Prior BaaS / embedded-finance integration experience. A background in payments, banking, or fintech operating across multiple jurisdictions. What You'll Gain Ownership of high-impact projects that directly unlock new markets for Unlimit. Exposure to the full fintech product landscape: acquiring, BaaS, wallets, crypto, and more. A global company with a strong engineering culture, agile mindset, and flat hierarchy. Collaboration with international teams across EU, LATAM, and APAC. Join Unlimit Team now!   Unlimit is an equal opportunity employer. We believe passionately that employing a diverse workforce is central to our success. We make recruiting decisions based on your experience and skills. We welcome applications from all members of society irrespective of age, sex, disability, sexual orientation, race, religion or belief.