The tool lives on the packer page itself: ▶ Open the .MOD UN/PACKER, nothing to install, runs straight in your browser.
If you want it faster, or you are working on a multi-hundred-MB compilation, reach for the native Rust build instead: tl2-mikuro-mod-packer-rs: a single exe, nothing to install, real multi-core parallelism and no 4 GB browser memory ceiling, typically several times quicker. Both are the same code and produce byte-identical output; the web edition simply wins on being instantly available, anywhere.