Senior Software Engineer, Back-End (Payments)

Role Description

We are looking for a Senior Software Engineer to join our Payments team — a critical engineering domain responsible for building, scaling, and evolving the payments infrastructure that powers every transaction across the Collectors ecosystem.

• This team owns the full lifecycle of payment capabilities:
• Integrating with and abstracting across multiple payment gateway providers (including Stripe and PayPal).
• Supporting payment methods spanning credit card, ACH, and digital wallets.
• Building both the APIs that downstream services depend on and the web application experiences that customers and internal tools rely on.
• You will work across backend APIs and modern frontend surfaces, partnering with product, design, and cross-functional engineering teams to deliver reliable, scalable, and secure payment experiences.
• This is a high-impact, high-visibility role touching grading order checkout, vault and consignment transactions, partner payouts, and customer wallet top-ups.
• You will have direct influence over architecture decisions, gateway integrations, and the quality bar for everything that ships.
• We believe there is significant value in onsite partnership and team collaboration; candidates within 1-hour commuting distance of the office may be expected to work onsite most of the time.

What You’ll Do

• Build and evolve multi-gateway payment integrations:
• Design, implement, and maintain integrations with multiple payment gateway providers — including Stripe, PayPal, and others.
• Build clean abstractions that minimize disruption when adding or swapping gateways.
• Own payment flows end-to-end from initiation through settlement, refund, and reconciliation.
• Deliver full-stack payment experiences:
• Develop backend payment services and APIs in C#/.NET.
• Build intuitive customer-facing experiences in React, Svelte, and TypeScript that power checkout and payment management.
• Collaborate closely with design and product to ensure every flow is accessible and conversion-optimized.
• Champion security, compliance, and resilience:
• Apply PCI-DSS best practices and resilient design patterns — including tokenization, idempotency, retries, and audit controls.
• Ensure secure and reliable payment processing at scale, partnering with Security and Compliance teams to maintain and advance our certifications.
• Take an AI-first approach to building:
• Leverage AI-assisted development tools throughout the software lifecycle to accelerate delivery, improve quality, and evolve engineering best practices.
• Architect for scale and observability:
• Design and operate distributed, event-driven services on AWS and Kubernetes.
• Use metrics, tracing, and alerting to maintain high availability and accelerate incident response.
• Drive cross-functional execution:
• Translate business requirements into technical solutions.
• Partner across Payments, Marketplace, Grading, Vault, and platform teams to deliver seamless payment experiences that connect the Collectors ecosystem.

Qualifications

• 6+ years engineering experience.
• Track record of designing, shipping, and scaling products that have measurable business impact.
• Ideally 2+ years operating as a Senior IC or equivalent technical leadership level at a high-growth company or a scaled consumer platform.
• Deep backend expertise in C# (.NET).
• Comfortable owning complex API surfaces, async patterns, and data consistency in distributed systems.
• Frontend experience in React, Svelte, and TypeScript.
• Strong fundamentals working with databases and data modeling, both relational (e.g. PostgreSQL) and NoSQL (e.g. DynamoDB).
• Familiar with Agile/Scrum methodologies.
• Payments or fintech experience.
• Distributed-systems depth.
• AI-first engineer.
• Observability-first mindset.
• Security-minded.
• Influential communicator.
• Bias for ownership.
• Passion for collecting is a plus.

Salary Range

The salary range for this position is $140,971-$228,870. Actual compensation on this range varies based on a variety of non-discriminatory factors, including location, job level, experience, and skill set. This role may be eligible for bonuses, commissions, or other forms of compensation; please ask your recruiter for details.

Benefits

• Health Insurance: All full-time employees are eligible to enroll in Medical, Dental, and Vision.
• Additional Benefits: Full-time employees are eligible for fertility, commuter, and educational assistance benefits.
• 401(K) Matching Plan: We offer a competitive 401k matching plan to support employees' future financial goals.
• Vacation: All salaried employees are eligible for flexible time-off.
• Holiday Pay: All regular, full-time employees are eligible for ten company paid holidays.
• Employee Discounts: Employees receive discounts on select grading services for approved submissions.
• Flexible Hours: Many teams offer flexible schedules with varying shifts and will work with you to accommodate your needs.
• Fun Working Environment: Team members are invited to participate in celebrations, holiday events, and team building activities.