Senior Backend Engineer (Node.js / Kotlin)

[Employer] 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.
[Employer] 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. [Employer] 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 [Employer] 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 [Employer] wallet - providing APIs for wallet synchronization, push notifications, referral and promotional programs, crypto payments, DeFi and staking integrations, and analytics pipelines.`

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.

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.

Benefits

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, excluding Russia and Belarus, with a schedule aligned with GMT+3;

• Competitive salary in EUR/USDT;

• Unlimited vacation;

• Birthday presents;

• Compensation for the purchase of necessary technical devices for the work;

• Paid sick leaves.

Originally posted on [Employer]

Timezone: UTC+1 to UTC+1.