Mirror Fractal Codec (MFC) is a lossless, domain-specific compression codec for asynchronous event-camera streams. 1.51 bits/event / 47.6× compression on the full N-MNIST benchmark (60,000 samples, bit-exact round-trip verified). 7.8 bits/event / 9.2× on DSEC automotive data (640×480 sensor). 0.55 ms per N-MNIST sample (WASM single-thread); <0.1 ms native. Version 0.3.28 ships pre-built CPython 3.11 wheels for manylinux_2_34_x86_64, macOS arm64, and Windows amd64 on PyPI as mfc-codec, plus a WebAssembly build powering the browser demo at https://codec.mirrorfractal.com. This Zenodo deposit archives the public Python/WASM distribution and the accompanying preprint. The Rust encoder sources remain private pending US Provisional Patent 64/034,974; the binary distributions on PyPI are licensed for evaluation and academic use. Public mirror (docs, examples, issues): https://github.com/MirrorFractal/codec Contact / commercial licensing: info@mirrorfractal.com