Reins - Fullstack Engineer

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