Zero-Egress Document Systems Using Client-Side WebAssembly

Cloud-based document processing services expose enterprise workflows to severe network latency overhead, recurring API financial costs, and catastrophic data breach liability through remote payload transit. To eliminate remote document egress, we introduce HandleMyFile, a zero-egress document manipulation architecture executing entirely within client browser threads via isolated WebAssembly and Web Worker pipelines. By binding DOM operations to in-memory buffers through detached worker transfer protocols, the system enforces complete mathematical non-interference over the network socket. Across an empirical benchmark of 490 diverse real-world documents from the Mozilla PDF corpus, our client-side architecture decisively outpaces cloud endpoints, yielding a statistically significant localhost speedup of 1.88x (paired two-tailed t(489) = 8.29, p < 0.0001, 95% CI [1.77x, 1.98x]), scaling to 24.84x on Wi-Fi and 61.97x on mobile 4G, while verifying 0.00 MB outbound transmission and 99.71% metadata sanitization. Key Contributions:1. Zero-Egress Architectural Design: In-browser execution pipeline guaranteeing |Net_out| = 0.2. Formal Security Guarantees: Non-interference proof over network sockets under the Dolev-Yao adversary model.3. Analytical Transit Latency Model: Mathematical characterization of the network vs. compute inflection point.4. Rigorous Empirical Benchmark: 490 real-world documents evaluated across multiple network regimes.5. Open Replication Artifact: Open-source benchmark suite, datasets, and statistical scripts.