Senior API Engineer - Polymarket US

About Polymarket

Polymarket is the world’s largest prediction market. It’s half "put your money where your mouth is," half search engine for the future.

We're growing fast – both in terms of volume (>$8B traded last year) and adoption as an alternative news source. Our ambition is to become a ubiquitous beacon of truth in global media and we need your help adding fuel to the fire.

About the Role

Polymarket is looking for an experienced API engineer to develop and deploy endpoints for our ISV customers. You'll build the critical systems that facilitate access to our CFTC-regulated exchange, working directly on REST and FIX API systems.

This is a high-impact role where you'll work directly with engineering teams, build systems that handle liquidity at scale, and help establish the technical foundation for our growing US Exchange business.

What You’ll Do

• Maintain API access to our US Exchange. Create systems that help ISV participants and institutional customers set market prices on the US Exchange.

• Oversee Onboarding of Market Makers. Partner closely with our growing Forward Deployed Engineering team to help market makers access the API.

• Manage FIX / REST / SDK Integrations. Architect and test systems for handling various institutional customers and access needs.

• Design for scale and compliance. Build systems that handle thousands of daily transactions while maintaining audit trails and meeting CFTC regulatory requirements.

• Collaborate with internal teams. Partner closely with operations, compliance, and product to understand workflows, gather feedback, and iterate quickly on tooling.

• Lead technical decisions. Participate in architecture discussions, code reviews, and help establish best practices for the team.

What We’re Looking For

• 3-10 years of professional software development experience

• Strong FIX / REST / SDK experience with direct previous projects

• Solid experience with AWS, Cloudfare, Kubernetes, Kafka

• Experience building data-heavy applications or tools

• Strong collaboration and communication skills—you work well with non-technical stakeholders

• Bias for action—all-in work mindset eager to work immediately on solving problems

• Builder's mindset—you take pride in creating tools that solve real operational problems

• (Plus) Background in fintech, payments, reconciliation systems, or regulated environments

• (Plus) Understanding of regulated exchange backend and audit requirements

• (Plus) Bachelor's degree in Computer Science or equivalent