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cside is a web security company leveraging browser intelligence and AI to detect sophisticated threats that traditional tools miss. The company processes billions of browser signals in real-time to identify malicious JavaScript, prevent account takeovers, and stop fraudulent account creation. Backed by $7.7M in pre-seed and seed funding, cside is trusted by major brands across universities, e-commerce, fintech, crypto, and SaaS.
As a Senior Full-Stack Developer, you'll build the product surface that transforms raw browser data into actionable security intelligence. You'll own features end-to-end across the stack: designing and implementing high-volume, low-latency APIs; building React dashboards that security engineers use daily; and working with real-time data pipelines to surface detections clearly without overwhelming users.
Key responsibilities include shipping features from API endpoints to customer-facing dashboards, designing systems that handle massive signal volume, turning complex security signals into intuitive interfaces, and improving performance and reliability at scale. You'll partner closely with product and security research teams to move detections from prototype to production, contribute to code review and technical standards, and own the full lifecycle: design, implementation, testing, shipping, measurement, and iteration.
You bring 5+ years building production web applications with real ownership, strong TypeScript skills across React and Node/similar backends, and experience with real-time or high-volume data systems. You understand performance deeply, can scope your own work and ship independently, write clearly in code and design docs, and have genuine interest in web security. You're based in the US with authorization to work, maintain at least 4 hours daily overlap with US Pacific time, and are willing to travel for 2-3 company offsites annually.
cside values transparency, integrity, and shipping quality products without cutting corners. The company offers quarterly offsites in tropical locations, generous work-from-home allowance, latest MacBook, stock options, market-rate seed-stage salary, and unlimited PTO. The team is invested in long-term career development and celebrates equal opportunity regardless of educational background, age, identity, or status.
