Senior Fullstack Engineer @ GPTZero | $140k - $210k + Equity

Senior Fullstack Engineer Our client is a fast-growing technology company building a leading AI-detection and content verification platform that helps organizations distinguish between human-written and AI-generated text. Using proprietary models fine-tuned on diverse writing styles, the platform analyzes content at the sentence, paragraph, and document level to provide clear, interpretable results. Their tools are trusted by millions of users across education, publishing, legal, recruitment, cybersecurity, and media. Core features include a browser extension for real-time detection, dashboard batch processing, API integrations, and visual highlighting of AI-detected text. By combining machine learning, experimentation systems, and intuitive UIs, the platform empowers users to uphold content authenticity, protect intellectual property, and combat AI-driven misinformation. They are expanding their New York team with experienced engineers who thrive in fast-moving environments, embrace responsibility, and are motivated by growth. In this role, you’ll work on high-impact features such as experimentation platforms and in-app notification systems, directly influencing user engagement and company growth. Their environment blends startup energy with engineering rigor—weekly hackathons, regular offsites, and a close-knit, collaborative team culture. What you’ll do: Design, develop, and maintain fullstack applications using React , TypeScript , and modern backend technologies Enhance their experimentation platform to drive product innovation and growth Build robust in-app notification systems and other growth-oriented features Collaborate with product, design, and machine learning teams to deliver seamless user experiences Participate in all stages of the product lifecycle—concept, implementation, testing, deployment, and monitoring Write well-tested, maintainable code and contribute to architectural decisions Mentor junior engineers and share best practices across the engineering team Experience required: Proven experience building production applications from backend to UI Expertise in React , TypeScript , and modern JavaScript frameworks (Next.js a plus) Strong understanding of databases (SQL, NoSQL, and text search) Track record of delivering features end-to-end in collaborative environments Strong communication skills and ability to work cross-functionally Bachelor’s degree in Computer Science or related field preferred Work eligibility in the US (H-1B transfer sponsorship available) Summary: Job name: Senior Full Stack Engineer Work type: Full-time Hours: Hybrid, 4 days/week in NYC office Location: New York, NY Compensation: $140K–$210K USD base + equity (~0.1%, $20K–$50K/year) Visa sponsorship: H-1B transfer sponsorship available Company size: ~15 engineers, growing Funding + investors: Well-funded, growth-stage Reporting to: Engineering leadership Interview process: Recruiter call Two-hour React take-home project (no AI assistance) Two to three engineering interviews Culture interview with CEO Reference checks