decircle

Fullstack Engineer

decircle

full-time

Posted on:

Location Type: Remote

Location: California • United States

Visit company website

Explore more

✨ AI Apply
Apply

Tech Stack

DartFlutterRuby on RailsSolidity

About the role

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

Requirements

  • 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
Applicant Tracking System Keywords

Tip: use these terms in your resume and cover letter to boost ATS matches.

Hard Skills & Tools
backend engineeringfull-stack engineeringSolidityAPI developmentACHwirescardsAML compliancesecurity best practicesthreat modeling
Soft Skills
problem-solvingattention to detailautonomycollaboration