Staff Fullstack Engineer

About PolymarketPolymarket 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 terms of volume ($21B traded in 2025) 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 RoleWe're building a dedicated growth engineering function at the org level, and this role sits at the center of it. Your mandate is user growth: owning the new user experience from first touch to first trade, reducing friction in the acquisition funnel, and building the surfaces that turn curious visitors into active traders. This is not a siloed frontend or backend job — you will work across the entire stack and cut into whatever territory needs cutting into.The team operates with a mission-driven structure. You will collaborate closely with product, data, and other engineering teams, but you are expected to drive, not wait. Growth at Polymarket is not a marketing problem — it is an engineering problem. The onboarding flow, the KYC experience, the ad-driven funnels that bring people from a sports broadcast into a live prediction market: all of it gets built here.What You'll DoOwn and iterate on the new user onboarding flow, from account creation through KYC completion, with a focus on activation rates and drop-off reductionBuild ad-driven funnel surfaces that route users from external campaigns directly into relevant market pages, coordinating with product on targeting logic and layoutShip fullstack features end to end — writing frontend UI, backend services, and third-party integrations — without needing work parceled out across teamsIdentify friction points in the user acquisition funnel using product analytics and experiment your way to solutions, measuring impact at each stepReview code and make architectural decisions within your domain without waiting for senior sign-off or a fully specced ticketCoordinate across engineering teams to get changes made in services you do not own, aligning stakeholders and keeping things movingRaise the technical bar on the growth team through code review, direct feedback, and helping less senior engineers scope and ship better workWhat We're Looking For7+ years of fullstack engineering experience, with real depth on both the frontend and backend — not just familiarity with one sideProven track record shipping user onboarding flows, KYC integrations, or acquisition funnel features, with measurable results you can speak toExperience working across teams in a larger engineering org, navigating ownership boundaries and getting things done without top-down coordinationStrong product instincts — you can look at a funnel, identify what is broken, and propose a fix without waiting for a product manager to hand you a specComfortable making technical tradeoffs at the system level, scoping across frontend, backend, and external services and choosing the right approach for the constraintClear communicator who can align engineers, product managers, and stakeholders on scope and priorities without creating unnecessary process(Plus) Experience with Web3 onboarding flows or crypto-native KYC and compliance tooling(Plus) Familiarity with prediction markets, financial platforms, or other high-stakes transaction products(Plus) Experience running growth experiments with A/B testing frameworks and interpreting results to drive next steps