Senior Backend Engineer, Payments

About Polymarket Polymarket is the world's largest prediction market platform. We enable individuals to express views on real-world events by trading on outcomes across politics, economics, sports, culture, and current affairs. Built as a peer-to-peer marketplace with no centralized “house,” Polymarket aggregates diverse opinions into transparent, market-based probabilities that reflect collective expectations about the future. We’re growing fast: both in volume ($21B traded in 2025) and in adoption as an alternative news source. Our ambition is to become a ubiquitous beacon of truth in global media, powered by fast, reliable, and deeply technical market infrastructure. About the role Polymarket is looking for a senior backend engineer to build and scale the payments infrastructure that powers deposits, withdrawals, and money movement across the platform. This role sits at the intersection of engineering and regulated financial operations, and requires the judgment to move fast without compromising correctness or auditability. You’ll be a high-ownership individual contributor working closely with Product, Compliance, and Design. What you’ll do Build payments infrastructure: Design and lead migrations from legacy or monolithic systems to reliable, distributed payments services (Go, gRPC, DynamoDB/MySQL) with no disruption to production money movement. Integrate with financial rails: Build and maintain integrations with payment processors, banking rails, and card networks to support deposits, withdrawals, and settlement. Ship regulated features: Partner cross-functionally with Product, Compliance, and Design to deliver high-stakes financial features such as KYC/EDD, fraud checks, and reconciliation. Own correctness and auditability: Take ownership of production on-call for money-movement systems where correctness, reliability, and auditability are non-negotiable. Drive team process: Mentor engineers, onboard new hires, and lead backlog grooming and tech-debt reduction efforts. Collaborate cross-functionally: Work closely with engineers across the platform to keep payments systems tightly integrated with the broader exchange. What we’re looking for Senior-level backend engineering experience with payments, fintech, or financial-data integrations (processors like Stripe, banking rails, card networks). Proven track record leading migrations from legacy/monolith systems to reliable distributed services (Go, gRPC, DynamoDB/MySQL) without production disruption. Experience partnering with Product, Compliance, and Design to ship regulated or high-stakes financial features (KYC/EDD, fraud, reconciliation). Comfortable owning production on-call for money-movement systems where correctness and auditability are critical. Track record of mentoring, onboarding, and driving team process (backlog grooming, tech-debt reduction). (Plus) Experience in crypto, prediction markets, or other high-growth regulated fintech environments. (Plus) Experience deploying systems in cloud environments (AWS/GCP) and using containers. Benefits Competitive salary & equity Unlimited PTO Full Health, Vision, & Dental coverage 401k match Hardware setup — new MacBook Pro, big display, & accessories