Built a browser-based file transfer tool after discovering the practical limits of pure P2P architectures and redesigning it around a faster, more reliable approach. * Started with WebRTC data channels for direct browser-to-browser transfers. Benchmarked against major P2P file-sharing tools and found consistent throughput limits caused by browser networking constraints rather than implementation quality. * Identified additional reliability issues with NAT traversal, carrier-grade NAT (CGNAT), and asymmetric consumer internet connections, which frequently degrade real-world P2P performance. * Redesigned the transfer path using Cloudflare Durable Objects to maintain stateful edge sessions and stream files through the nearest edge location, significantly improving transfer speed and reliability while preserving a browser-only experience. * Kept pure P2P as an optional mode for privacy-focused users who prefer direct peer-to-peer transfers. * Implemented resumable file transfers by tracking byte offsets, allowing interrupted transfers to continue from the last completed position instead of restarting. * Grew the platform to 500+ organic users across multiple countries with zero marketing spend.