Senior Software Engineer - Payments

Department: Engineering

Location: Portugal, Malta, Spain, Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Ireland, Italy, Kosovo, Montenegro, Romania, Serbia

Employment Type: FullTime

About Block Labs

Block Labs is a premier technology studio operating at the bleeding edge of Web3, Artificial Intelligence, and iGaming. We don't just ship features; we engineer high-scale, production-grade platforms that power the next generation of digital products.

We are a collective of senior engineers, product strategists, and builders who refuse to compromise on architecture. Whether we are designing autonomous multi-agent AI systems, building decentralized financial infrastructure, or architecting high-frequency iGaming platforms, our standard is excellence.

We move fast, but we build for the long term. If you are looking to work alongside a team that values deep technical expertise, thoughtful system design, and product ownership, Block Labs is where you belong.

About The Role

We are building a high throughput, multi-tenant payments platform powering deposits, withdrawals, balances and settlements across multiple brands and partners.

As a Full Stack Software Engineer in the payments team, you will play a key role in accelerating third party integrations, improving authentication and transaction flows, and reducing time to market for new suppliers. You will work across a multi-language environment, contributing to Go based core services, React frontend applications, TypeScript modules and auxiliary PHP services that support the broader platform.

This role is focused on ownership, execution speed and continuous system improvement in a financial context where reliability and integrity are critical.

Key Responsibilities:

• Design, implement and improve backend services supporting payment and transaction flows.

• Develop and refine frontend components that power deposit, withdrawal and account experiences.

• Own end to end third party payment and supplier integrations.

• Implement and maintain secure authentication, webhook validation, signature verification and callback handling.

• Improve integration architecture and internal tooling to reduce onboarding time for new providers.

• Ensure transactional integrity, idempotency and reliability across all payment flows.

• Identify bottlenecks that slow down integration and delivery cycles and propose structural improvements.

• Write clean, efficient and maintainable code with strong focus on scalability and resilience.

• Collaborate closely with backend, frontend, QA and DevOps teams to deliver reliably and quickly.

• Manage individual project priorities, deadlines and deliverables.

About You:

• 4+ years of experience as a Full Stack Engineer working on backend and frontend systems.

• Strong experience building and maintaining APIs and transactional backend services.

• Experience contributing to modern frontend applications such as React.

• Comfortable working in environments that include Go, TypeScript and PHP.

• Proven experience integrating third party APIs, ideally payment providers or financial services.

• iGaming, fintech or other high transaction system experience is required.

• Solid understanding of authentication flows, external callbacks, webhooks and idempotent systems.

• Pragmatic mindset focused on shipping and improving time to market.

• Strong debugging and problem solving skills.

• Comfortable owning a feature or integration from design to production.

• Fluent in English, both spoken and written.

Nice to Have:

· Experience with cryptographic key management, wallet abstractions, or transaction signing flows.

· Background in fintech, DeFi, or crypto exchange infrastructure.

· Familiarity with event-driven systems, Kafka, or message queues.

· Prior experience designing APIs for multi-tenant or white-label products.

What kind of culture can I expect?
Mature, mission-driven, and low-ego. We value clarity over noise, outcomes over theatrics, and pace without chaos. If you’re one of the smartest minds in your craft and want to build with other experts, you’ll feel at home here.