About the Position

Solution Architect (Java, AI-native backend, FinTech)

Belgrade

Engineering – Architecture /

Full-Time /

On-site

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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.

About the Role

Unlimit is undergoing a deep technology transformation. As a global fintech with a robust suite of products - including card acquiring, banking-as-a-service, payment gateways, crypto solutions, and wallets - we’re rebuilding our core backend platforms to be AI-native, modular, and cloud-agnostic.

We’re seeking a forward-thinking and hands-on Solution Architect to lead this transformation from within. This is a strategic yet execution-driven role: you’ll help define and implement next-generation architecture that’s scalable, resilient, and designed with real-time AI capabilities.

You’ll work at the intersection of architecture, infrastructure, and delivery, collaborating closely with Product, DevOps, Engineering, and Data teams. Your work will directly shape systems that serve thousands of merchants globally - with near-zero downtime, built-in observability, and seamless integration of AI agents into critical paths. This is a rare opportunity to join Unlimit at a pivotal point and define the future of financial infrastructure.

Responsibilities

Take ownership of solution design for backend systems powering payment products (card acquiring, wallets, crypto, BaaS).
Design and maintain architecture that is AI-native and cloud-agnostic, aligned with modern security, scalability, and compliance standards.
Partner with product managers, engineering leads, QA, and analysts to translate business needs into modular architectural designs.
Build out documentation, high-level solution diagrams, system interface contracts, and component-level specifications.
Act as a key contributor to API design and service decomposition efforts.
Guide cloud migration and infrastructure evolution (AWS-based stack, with Kubernetes, GitLab CI/CD, Terraform).
Ensure systems enable zero-downtime deployments, automated rollbacks, and scalable horizontal patterns.
Conduct architectural reviews, technical assessments, and work closely with delivery teams to implement designs.
Act as a thought leader and “tech compass” across engineering functions, driving architectural maturity and platform modernization.
Proactively identify technical debt and long-term design risks; propose mitigation strategies.

Requirements

Core Skills
- 6+ years of experience in architecture roles, preferably in fintech or high-availability distributed systems
- Proven experience designing scalable backend systems in AWS or hybrid cloud environments
- Strong hands-on background in backend development (Java), DevOps, or cloud infrastructure
- Deep understanding of distributed systems, event-driven architectures, microservices, CI/CD pipelines, and observability practices (Grafana, Prometheus)
- Solid experience with Kubernetes, Terraform, and GitLab CI/CD
- Experience participating in and driving system design reviews across multiple teams
- Strong stakeholder communication skills and ability to align technical and business requirements
- Comfortable working in fast-paced, cross-functional environments (LATAM, EU, APAC collaboration)
AI & Emerging Technologies
- Practical experience integrating AI/ML components into backend systems (e.g., AI pipelines, agent-based integrations, MLOps)
- Demonstrated awareness of AI-driven engineering practices and emerging AI technologies
- Hands-on experience leveraging AI tools (LLMs, AI-assisted development tools, automation frameworks) to improve productivity, system performance, or architectural decision-making
Domain Experience
- Background in financial services, payment gateways, acquiring, digital wallets, or other regulated environments

What You’ll Gain

A unique opportunity to drive AI-native backend transformation at scale
Exposure to the full fintech product landscape: card processing, crypto, wallets, BaaS
Work in a global company with a strong engineering culture, agile mindset, and flat hierarchy
Collaborate with international teams that deeply value architecture, resilience, and innovation
Strong support for async cross-timezone collaboration

We Offer

Competitive salary
Full-time employment
On-site work in Belgrade, Serbia
Opportunity to shape the future of financial infrastructure

About the Company

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.

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.

Join Unlimit Team now!

Solution Architect (Java, AI-native backend, FinTech)

Job description