Senior Backend Engineer (Node.js + Kotlin)

Tangem is a high-tech company in the blockchain sector was founded in 2017, headquartered in Zug, Switzerland, with branches in North America, Eastern Europe, and APAC.

Tangem started with the idea of bringing digital assets to the masses using a unique combination of a smartcard-based hardware wallet and mobile applications. Company owns and promotes the technology of hardware cold-wallet for digital assets with secure and simple UX in 220 countries today. Our customers enjoy setup time within 1 minute with the ultimate security level for digital assets on their wallet. Tangem solutions offer multi-support of a growing number of thousands of tokens by a single wallet. SBI Crypto Investment Ltd., the digital asset venture investment company wholly owned by SBI Holdings Inc., has invested $15 million into Tangem in 2019 for mass adoption of blockchain technology.

About the Role: We're looking for a Senior Backend Engineer to join our backend team and take ownership of building, maintaining, and evolving our microservices. You'll work across both stacks - maintaining existing Node.js services and building new ones in Kotlin - contribute to architecture decisions, and help us maintain high standards of quality and reliability.

About the Project: Our backend is a set of microservices that power the Tangem wallet - providing APIs for wallet synchronization, push notifications, referral and promotional programs, crypto payments, DeFi and staking integrations, and analytics pipelines.

Responsibilities:

• Design, build, and maintain scalable backend services across Node.js and Kotlin stacks.
• Write clean, well-tested code - testing is a first-class concern.
• Own features end-to-end: decompose tasks and make technical decisions.
• Maintain and evolve existing NestJS services while building new services in Kotlin/Spring.
• Occasionally build internal tools and admin interfaces using React.
• Collaborate with product, DevOps, and engineering teams on cross-functional delivery.
• Participate in code reviews, architecture discussions, and continuous improvement of system reliability and observability.

Requirements:

• Strong production experience with Kotlin or Java, and Spring.
• Comfortable working with Node.js and NestJS for maintaining existing services.
• Strong testing practices.
• Deep understanding of software architecture, design patterns, and microservices.
• Experience with AWS services - Lambda, SQS, S3, and others.
• Experience with containerized environments and Kubernetes.
• Good communication and collaboration skills.

Nice to have:

• Experience in fintech, crypto, or payment systems is a plus.

Tech Stack:

• Current services: TypeScript, Node.js, NestJS, TypeORM.
• New services: Kotlin, Spring.
• Infrastructure: AWS, Kubernetes.
• Databases & Storage: PostgreSQL, Redis.
• Messaging: SQS, BullMQ.
• Admin tools: React.

Why Join Us:

• Work alongside a team of skilled engineers on a product used by millions.
• Build with a modern, thoughtfully chosen tech stack.
• Minimal bureaucracy and fast decision-making.
• Real ownership - influence the product, architecture, and business outcomes directly.
• Room to grow technically and shape the platform's future.

What We Offer:

• Stability, development, participation in the future unicorn's growth.
• Remote work from anywhere in the world.
• Competitive salary in EUR/USDT.
• Unlimited vacation.
• Birthday presents.
• Compensation for the purchase of necessary technical devices for the work.
• Paid sick leaves.