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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Senior Software Engineer, Back-End (Payments) - **Company:** Collectors Holdings, Inc. - **Location:** San Francisco, CA, United States (Remote available) - **Experience:** Expert - **Salary:** $140,971.0 - $228,870.0 - **Contract:** Permanent contract - **Skills:** .NET Framework, Application Programming Interfaces (APIs), Artificial Intelligence, Amazon Web Services, User Authentication, C Sharp (Programming Language), Code Generation, Databases, Software Debugging, Software Design Patterns, Distributed Systems, Amazon DynamoDB, Video Game Development, Design of User Interfaces, Human-Computer Interaction, PostgreSQL, NoSQL, Payment Gateway, Payment Service Provider, PCI Data Security Standards, Scrum Methodology, Systems Development Life Cycle, Query Optimization, Svelte, Software Engineering, Data Streaming, Tokenization, TypeScript, Web Applications, Datadog, ReactJS, Backend, Event Driven Architecture, Stripe, Kubernetes, Apache Kafka, Front End Software Development, Text Summarization, Marketplace, Dynatrace, Microservices - **Published:** October 31, 2026 - **Apply:** https://www.careerbuilder.com/job-details/senior-software-engineer-back-end-payments-san-francisco-ca--48e460f2-92a0-4060-97f6-3b20adc9eda2 ## About the Role Software Engineering, Authentication, Sales, Video Games, Ecosystems, Software Engineering, Application Programming Interface (API), Credit Cards, Internet Application, User Interface/Experience (UI/UX), * 6+ years engineering experience. You have a 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). You're comfortable owning complex API surfaces, async patterns, and data consistency in distributed systems. * Frontend range in React, Svelte, and TypeScript. You build clean, responsive payment UIs and understand the nuances of state management, form handling, and secure client-side data flows. * Strong fundamentals working with databases and data modeling, both relational (e.g. PostgreSQL) and NoSQL (e.g. DynamoDB). You're comfortable designing schemas, writing efficient queries, and choosing the right storage layer for the problem. * Familiar with Agile/Scrum methodologies. You're comfortable working in iterative delivery cycles, participating in sprint planning, and adapting quickly to changing priorities. * Payments or fintech experience. You understand gateway integrations, idempotency, webhook reliability, tokenization, and PCI compliance in production environments. * Distributed-systems depth. You've designed and operated microservices and Kafka-based event-driven architectures, run workloads on Kubernetes, and know your way around the AWS ecosystem. * AI-first engineer. You build with AI tooling across the SDLC - from planning and code generation to review and debugging. You have a clear, practiced point of view on how AI raises the quality bar and accelerates delivery. * Observability-first mindset. You instrument what you ship using Datadog or similar tools. You're comfortable building dashboards, setting up monitoring/alerting, and using distributed tracing to debug production issues. * Security-minded. You treat payment security as a first-class engineering concern, not an afterthought. * Influential communicator. A strong written and verbal communicator with sharp analytical and troubleshooting instincts - you align engineers, product partners, and stakeholders without direct authority, make crisp calls, and bring people with you. * Bias for ownership. You have an extreme ownership mindset and will wear any hat required to get the job done. You thrive in a fast-moving, self-directed environment - you set the bar, hold it, and take full accountability for outcomes. * Passion for collecting is a plus. ## 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, and 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. Payments is the financial backbone of our marketplace - 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, and candidates within 1-hour commuting distance of the office may be expected to work onsite most of the time. Additional details will be discussed during the recruiting process. 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 - building clean abstractions that minimize disruption when adding or swapping gateways, while owning 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 while building intuitive customer-facing experiences in React, Svelte, and TypeScript that power checkout and payment management, collaborating 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 - to 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, using metrics, tracing, and alerting to maintain highly availability and accelerate incident response. * Drive cross-functional execution: Translate business requirements into technical solutions and partner across Payments, Marketplace, Grading, Vault, and platform teams to deliver seamless payment experiences that connect the Collectors ecosystem., U.S. residents: for disclosures relating to personal information we collect during the employment application and recruitment process, please see our Privacy Notice for U.S. Applicants.