Staff Full Stack Engineer

Who Our Client Is: Our client builds the geolocation compliance layer for regulated online sports betting and gaming. Before an operator can accept a wager, it must prove the player is physically located where the law requires and show this to a regulator on demand. Our client solves this in real time and at scale for some of the largest betting operators in the US and internationally. The work combines distributed systems, fraud detection and security engineering, and every release is filed with state gaming regulators before it reaches production. What Our Client Needs: Our client is seeking a Staff Full Stack Engineer to build features end-to-end, from the SDK running on a player's device to the backend services that decide whether a wager can be placed. A new detection signal starts in the SDK, travels through the APIs, is evaluated by backend rules, lands in the data pipeline and must be explainable to customers in the Portal. This role carries that whole path. It is a senior individual contributor role with no direct reports. It's a hybrid role based in Philadelphia, open to candidates in the Philadelphia to New York City corridor. Most of the engineering team sits outside the US, about 8 hours ahead of US Eastern, so much of the collaboration is remote and async, with occasional international travel. What You'll Do: Design, build, test and ship features end-to-end across the SDK, Portal, APIs, backend services and data pipeline Take customer problems from report to verified fix, following behavior across system boundaries rather than handing it off Contribute production code to Java/Spring backend services, the Kotlin Multiplatform SDK and its native layers, and the Angular/TypeScript Portal and JavaScript Web SDK Ensure consistent behavior and feature parity across native and web platforms Raise the technical standard through code review, pairing and documenting architectural decisions Own what you ship in production, including performance, on-call, incident response and root-cause resolution Partner with Product, QA, SRE and Compliance to deliver reliable releases that meet regulatory requirements Drive async collaboration across time zones and use AI development tools with sound judgment and guardrails What You'll Need: Staff-level experience delivering complex features end-to-end across multiple layers of a production system Strong backend expertise in Java and Spring/Spring Boot, including REST APIs and microservices Strong client-side expertise in TypeScript and JavaScript, including a modern framework such as Angular Hands-on client SDK development experience (Kotlin, Kotlin Multiplatform or equivalent native), including SDKs consumed by third-party apps Experience building and operating low-latency, high-throughput, mission-critical systems Strong cloud experience (AWS, Kubernetes, Docker), plus NoSQL and streaming/messaging technologies Security-conscious engineering, including TLS, token management, request signing and device attestation (Play Integrity, App Attest) Strong testing and CI/CD practices, including Git branching, release cutting and merge discipline Fluency with AI development tools, including validating and overriding AI-generated work Excellent written communication and the ability to explain complex system behavior clearly Preferred: fraud detection or anti-spoofing, emulator/remote-desktop detection, React Native or Flutter bridging, geospatial, regulated environments, iGaming, or startup experience What They Offer: Compensation range of $195,000 to $230,000 Hybrid work arrangement based in Philadelphia, PA, working with a globally distributed team Comprehensive medical, dental and vision insurance 100% employer-paid employee health premiums and 50% for eligible dependents 3 weeks of paid vacation starting in the first year, plus paid sick time and holidays 401(k) with a strong company match 100% company-paid life insurance, AD&D and short-term disability, plus optional long-term disability Panna Knows LLC