Senior Backend Engineer, Blockchain

Blackbird Labs Inc • New York, NY

80d • $180,000 - $220,000

About The Position

At Blackbird, we believe every guest should feel like a VIP the moment they walk into a restaurant. Whether it’s last-minute tables, welcome drinks, off-menu items, or exclusive perks, we’re building a platform that helps restaurants identify, connect with, and reward their guests in meaningful and personalized ways. Our vision? The more you check in at your favorite spots, the more you unlock—from unique rewards to seamless direct messaging for reservations. With each visit, you’ll earn $FLY, our universal rewards currency, which you can use across our network of outstanding restaurants. As a Senior Backend Engineer, you’ll bridge traditional fintech and blockchain technologies to build our next-generation payments infrastructure. You’ll collaborate with product managers, designers, and fellow engineers to define and execute the technical vision behind our crypto payments and loyalty platforms. You’ll shape key architectural decisions, establish engineering best practices, and help scale secure, user-friendly Web3 payment experiences. We’re looking for someone who thrives in a fast-paced, high-ownership environment and is passionate about building products that seamlessly bridge the on-chain and off-chain worlds.

Requirements

• 5+ years of experience building and deploying backend APIs.
• Strong proficiency in Kotlin or another statically typed JVM language.
• Working knowledge of Solidity, smart contract design, and EVM-based ecosystems.
• Experience designing RESTful APIs and distributed systems using domain-driven design principles.
• Familiarity with blockchain architectures, smart contract interactions, wallet authentication flows, and transaction signing.
• Strong attention to detail and commitment to delivering secure, high-quality user experiences.
• Comfortable working cross-functionally with product, design, and engineering teams.

Nice To Haves

• Experience with Spring Boot, Hibernate, and asynchronous event-driven architectures.
• Familiarity with the U.S. payments ecosystem, including debit, credit, and ACH processing.
• Exposure to AWS infrastructure, Terraform, and CI/CD pipelines.
• Understanding of cryptographic primitives (signatures, hashing, key management).
• Experience with embedded wallet SDKs (e.g., MetaMask, WalletConnect) or user identity systems (OAuth, Web3 login flows, Auth0).
• Experience building in-app crypto wallets or integrating on-chain/off-chain loyalty systems.

Responsibilities

• Design, build, and maintain backend APIs that integrate blockchain transactions with traditional payment systems.
• Integrate on-chain wallet services, managing wallet lifecycle events, transactions, and user authentication.
• Implement secure and scalable solutions for on-chain payment flows, transaction signing, and state reconciliation.
• Work with smart contracts, blockchain oracles, and data providers to facilitate reliable on-chain interactions.
• Uphold and promote backend best practices with a focus on security, testing, and reliability.
• Mentor engineers and foster a collaborative, growth-oriented team culture.
• Participate in product and design discussions, providing backend and blockchain perspectives on implementation and feasibility.

Benefits

• Full time offers from Blackbird may also include stock options, benefits (including medical, dental, vision, flexible time off, 401(k)), and some not-so-standard, extra-fun perks — subject to applicable taxes and based on eligibility.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior