About the role

Role overview

Backend Software Engineer joining Rain’s crypto/fintech team. You’ll shape the technical and product roadmap while building scalable, secure backend systems and integrating with blockchain protocols and smart contracts.

Responsibilities

Build and maintain backend infrastructure
Integrate backend systems with smart contracts across multiple blockchain networks
Drive technical and architectural decisions for scalability and security
Collaborate with product teams to implement and improve features
Participate in code reviews, testing, and documentation
Stay current on emerging blockchain and DeFi trends
Support the technical roadmap and platform direction

Requirements

Proven experience with Node.js and backend technologies
Strong server-side architecture and backend fundamentals
Experience with RESTful APIs and microservices
Familiarity with blockchain concepts, smart contracts, and DeFi protocols
Strong problem-solving skills and attention to detail
Clear communication and strong collaboration skills
Builder mindset; interest in experimentation and side projects

Nice to have

Solidity and/or Rust experience
Prior smart contract development experience (not required)
Experience or interest in fintech, neobanks, or card issuing

Benefits

Unlimited paid time off (minimum 10 days annually)
Flexible work, including remote options
Comprehensive health/dental/vision insurance; company-paid life insurance
Equity options
Access to Rain Cards for product testing
Health and wellness stipends
Team summits

About Sundayy

Sundayy (Rain) is building fast and accessible ways for people to spend crypto in the real world, combining cryptocurrency with fintech. The company operates at the intersection of crypto, DeFi, and payments, backed by investors from both industries, with a small team of experienced builders. Engineers may be based in New York City, but the company is open to fully remote candidates.

Backend Engineer (Node.js, API)

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