A developer built a free derivative calculator using Next.js 15 and React 19 to bypass paywalls on existing tools. The project delivers step-by-step solutions without subscription fees, targeting students and developers who need reliable math verification.

Performance was a major hurdle. Complex derivatives caused UI lag until the developer moved calculations to Web Workers, freeing up the main thread. This kept the interface responsive even during heavy computation. The result is a smooth, 60fps experience.

Beyond speed, the app features step-by-step breakdowns of calculus rules, interactive graphs, and smart input handling. These tools help users visualize and understand derivatives in real time. The developer now seeks feedback on UX and graph interaction from the community.