Senior Backend Developer

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 RoleYou will own two production-critical services on Tangem's on-chain product surface:

• A DeFi yield product that lets Tangem users earn on their crypto through leading EVM lending protocols, directly from the mobile app — without giving up custody of their keys.
• A gasless transaction service that lets users sign normal on-chain transactions but pay the gas fee in ERC-20 stablecoins (USDC, USDT, etc.) instead of the native token. The service relays the signed transaction to the chain on the user's behalf.

Both services manage service-side signing wallets and move real user funds. Correctness, security awareness, and operational discipline are non-negotiable.

Current Technology Stack: Node.js, Nest.js, TypeScript, TypeORM, PostgreSQL, Redis, Ethers.js, AWS

Responsibilities:

• Add support for new chains, new fee tokens, and new yield protocols;
• Build the backend layer that signs, broadcasts, and monitors on-chain transactions;
• Implement meta-transaction flows on top of standards like EIP-712 and EIP-7702;
• Handle on-chain event ingestion through webhooks and background jobs;
• Own production releases — migrations, rollback plans, RPC failover;
• Write unit, integration, and E2E tests, instrument services for observability;
• Participate in planning, estimation, and architecture decisions.

Requirements:

• Strong production experience with Node.js and a modern framework like NestJS;
• Hands-on experience building on EVM chains with Ethers.js or viem;
• Familiarity with the EVM transaction model — signing, gas, nonces, RPC failover;
• Experience with PostgreSQL and writing efficient SQL;
• Solid understanding of common application security vulnerabilities;
• Experience writing unit and end-to-end tests;
• Experience with monitoring, logging, and debugging production issues.

Nice to have:

• Background in DeFi infrastructure;
• Familiarity with modern transaction / meta-tx standards like EIP-7702, ERC-2771, ERC-4337;
• Experience with distributed locking and concurrency primitives.

What We Offer:

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

Feel free to send you CV to Ivan - vkolesnikov@tangem.com