Senior Backend Engineer; Blockchain Integrations & Wallet Infrastructure

About Reap

Reap is a global financial technology company headquartered in Hong Kong with employees across multiple countries. We enable financial connectivity and access for businesses worldwide by combining traditional finance with stable coins for efficient money movement. Through our stablecoin‑powered corporate cards, payments, and expense management tools, we streamline financial operations and help businesses scale. Our APIs enable businesses to integrate stablecoin‑enabled finance into their own products and services—from issuing Visa cards to facilitating cross‑border payments.

Backed by leading investors including Index Ventures and Hash Key Capital, Reap is building the future of borderless, stablecoin‑enabled finance.

We’re looking for a Senior Backend Engineer who’s fluent in Type Script/Node.js and excited to build production‑grade systems that interact with live blockchains. You’ll lead the buildout of the core backend and infrastructure behind our multi‑chain platform—powering stablecoin‑backed payments, wallet infrastructure, and card‑related services for global businesses.

This role blends hands‑on backend engineering with Web3‑native systems work
: integrating across EVM chains, Solana, and TRON
, building gas abstraction / relayer infrastructure (including account abstraction patterns
), and partnering closely with product and other engineers to ship end‑to‑end. If you love owning complex systems—from API design and reliability to on‑chain monitoring, incident response, and continuous improvement—this role is for you.

• Core Platform Design:
  Design, develop, and deploy scalable applications in our AWS environment, ensuring they meet business requirements and adhere to high‑quality standards.
• Multi‑Chain Integration:
  Architect and maintain robust integrations with multiple blockchains, specifically EVM‑compatible chains (Ethereum, Base, Polygon), Solana, and TRON.
• Gas Abstraction & Relayer Infrastructure:
  Build and manage infrastructure to support sponsored (gasless) transactions. Implement Account Abstraction (ERC‑4337 / EIP‑7702) patterns to enable seamless user onboarding and fee subsidization across all supported chains.
• Wallet Infrastructure & Security:
  Lead the integration with enterprise‑grade Wallet‑as‑a‑Service (WaaS) and custody providers. Orchestrate programmable signing flows, and ensure secure implementation of embedded wallets.
• Collaboration:
  
  Work closely with cross‑functional teams—including product managers, designers, and smart contract engineers—to ensure seamless product development from concept to deployment.
• Observability & On‑Chain Monitoring:
  Build functional monitors and alerts for both off‑chain services (AWS) and on‑chain events (monitor pending tx pools, gas price spikes, and reorganization events). Investigate production incidents and apply learnings to code.
• Continuous Learning:
  Stay updated with the latest industry trends (e.g., L2 scaling solutions, new EIPs) to ensure our tech stack remains modern and competitive.

Minimum of 6 years in backend development, with at least 2+ years dedicated to production‑grade Web3/Crypto engineering. Proven track record of shipping products that interact with live mainnets (not just testnets).

• Strong knowledge in scalable software application design, API design (REST/Graph
  
  QL), and microservices architecture.
• Proficiency with Node.js, Type Script or NestJS.
• Deep understanding of relational databases (Postgre
  
  SQL, MySQL) and ORM frameworks.

• Chain Interaction:
  Deep familiarity with JSON‑RPC standards and client libraries (e.g., viem, ethers.js for EVM; @solana/web
  3.js for Solana).
• Transaction Management:
  Expertise in handling nonces, gas estimation, transaction replacements, and re‑org handling in a high‑throughput multichain environment.
• Embedded Wallets & Custody:
  Experience integrating programmable MPC (Multi‑Party Computation) wallets or embedded wallet solutions. Understanding of policy engines (allow lists, spending limits) and programmatic key signing.
• Gasless Architecture:
  Solid understanding of relayers, bundlers, and paymasters.…