Reins - Fullstack Engineer

Reins is building an enterprise stablecoin account that looks and feels like a first-class business bank account, while giving companies the benefits of stablecoin rails and self-custody . Reins makes stablecoins operationally simple for businesses, providing familiar banking features such as ACH, wires (and global equivalents like SEPA), cards, multi-level permissions, approvals, and AML/compliance workflows-combined with stablecoin-native advantages like instant 24/7 global settlement , better control via self-custody , and access to lending, insurance, and exchange markets as DeFi infrastructure matures.

Role Overview
You'll work directly with founder and CEO Sebastian Delgado (co-founder of Fei Labs), taking ownership of meaningful chunks of backend, full-stack, and security work. The role is flexible:

• Full-stack engineer (preferred)
• Backend engineer
• Product/frontend contributor (optional)

Focus areas are prioritized as follows: security & smart contracts, full-stack, backend, and product/frontend. Infrastructure/devops is not a current priority.

Backend & Integrations

• Design and build backend services connecting custody, fiat rails, policies, and operational workflows
• Implement and maintain APIs and services for ACH, wires, cards, permissions, AML/compliance workflows, and reporting

Smart Contracts & Security

• Implement and review Solidity smart contracts, focusing on correctness, safety, and upgradeability
• Contribute to threat modeling, security reviews, and audit/vendor management

Product & Full-Stack Work

• Collaborate on the design and implementation of customer-facing applications (currently Dart/Flutter )
• Translate user and operational needs into product and UX decisions, especially around permissions, approvals, and money flows

Security & Audit Participation

• Own parts of audit/security review processes for your areas of the stack
• Coordinate with external security firms
• Build internal systems and processes with a security-first mindset appropriate for handling customer funds

• Strong background as a backend or full-stack engineer , ideally in early-stage fintech (Plaid, Brex, Ramp, modern neobanks)
• Experience with crypto infrastructure, wallets, or stablecoin projects
• Proficiency in Solidity smart contracts or a willingness to contribute to security-critical logic
• Familiarity with APIs, integrations, and operational workflows (ACH, wires, cards, permissions, AML/compliance)
• Ability to collaborate on frontend/product work is a plus (Dart/Flutter experience beneficial)
• Strong understanding of security best practices for handling customer funds
• Excellent problem-solving, attention to detail, and autonomy in early-stage environments

Preferred Backgrounds

• Early engineers at crypto infra/wallet/stablecoin companies
• Strong backend/full-stack engineers from top fintechs who are crypto-native