Senior Software Engineer - Cards Integration

From the historical origins of Diners Club to modern tap-to-pay infrastructure, credit and debit cards represent a core promise: rapid authorization, high reliability, and absolute correctness in money movement.

At Mercury, cards are the primary way our business customers spend money. The Cards Integration team owns the entire lifecycle of Mercury Debit and IO cards—from card issuance and physical shipping to real-time authorization, spend controls, settlement, clearing, dispute management, and underlying financial infrastructure.

As a Senior Software Engineer, you will join a full-stack engineering team responsible for running mission-critical backend systems held to four nines (99.99%) of reliability. You will lead projects from technical spec to production deployment, architect high-throughput systems, and write clean, resilient code in Haskell and TypeScript.

Key Responsibilities

• End-to-End Technical Leadership: Drive projects from concept to tech spec, implementation, and launch alongside Product Managers, Engineering Managers, and cross-functional partners.
• Card Domain Systems Architecture: Deep-dive into card mechanics under the hood—including real-time authorization loops, clearing, settlement, risk screening, and dispute processing.
• Full-Stack Feature Engineering: Build high-reliability backend microservices and intuitive customer-facing controls across Mercury’s web and mobile card experiences.
• Operational Excellence & Observability: Monitor, support, and improve high-availability infrastructure using advanced telemetry, metrics, and incident runbooks.
• Mentorship & Quality Standards: Raise the engineering bar by conducting thorough design/code reviews, pair programming, and mentoring junior/mid-level engineers.
• Cross-Functional Collaboration: Partner directly with Product, Design, Risk, Compliance, Operations, and Customer Success teams to deliver compliant, user-centric financial tools.

Requirements

Experience & Technical Capabilities

• Proven track record as a Full-Stack or Systems Engineer with a product-focused mindset and a history of shipping complex systems.
• Strong systems architecture background, with the ability to articulate architectural decisions, technical trade-offs, and failure modes clearly.
• Experience building and maintaining high-correctness systems where failure carries real financial or operational consequences.
• Professional experience with or readiness to master Mercury’s core tech stack (Haskell for backend services and TypeScript for web/full-stack applications).
• Excellent communication skills with a collaborative, pair-programming-oriented work style.

Mindset & Engineering Culture

• Passion for maintaining four nines of uptime and zero-drift financial reconciliation.
• Comfortable working in a team environment built on high ownership, low ego, and continuous feedback.

Bonus Qualifications

• Hands-on software engineering experience in Fintech, payment processing, acquiring, or card issuing platforms.
• Prior experience working with banking partners, card networks (Visa/Mastercard), or payment gateways.

Total Rewards & Workplace Model

• Workplace Model: 100% Remote across the US and Canada.
• Compensation Philosophy: Competitive market-rate base salary coupled with meaningful company equity (RSUs/Stock Options) updated regularly using industry survey data.
• Benefits: Comprehensive health coverage, retirement planning, generous PTO, and flexible remote work setups.