Cache Me If You Can

NapkinCloud — Sketch. Test. Improve. NapkinCloud is a Meta-powered architecture workbench for founders and backend teams. It turns a system diagram into an editable, reproducible traffic experiment so builders can identify bottlenecks and compare a tested repair against the original. Upload a hand-drawn or digital architecture diagram, review the extracted components and connections, and configure traffic, service capacities, queues, deadlines and performance targets. Run a baseline, then let Meta propose bounded changes such as eligible-read caching, API replicas or independent tenant database partitions. Each candidate runs against the same workload and random seed, making before/after comparisons meaningful. The workbench shows animated request flow, latency and failure metrics, bottleneck findings, stress cases, an explanation and a generated architecture illustration. Users can export evidence and reopen browser-local saved runs. Three sample SaaS cases and a deterministic simulator work without an API key. The key design principle is that the simulator determines the numbers: model prose and generated artwork cannot set performance results. Failed repairs remain visible, added resources and assumptions are explicit, and a separately labeled bounded verification search can test partition counts when model candidates are insufficient. Built with JavaScript and a Node.js local backend, with a Cloudflare Worker deployment target. API credentials stay server-side. Results are simulations, not production benchmarks; the tool helps test architecture hypotheses before committing to infrastructure changes.