Elfshaker is a version control system designed for binaries, which stores snapshots of directories into highly-compressed pack files and provides fast on-demand access to the stored files. It is particularly useful for storing similar files, such as object files from an incremental build. The system achieves high compression ratios and fast access times, making it suitable for use cases like storing builds of a commit history. Elfshaker is written in Rust and is compatible with various Linux platforms, macOS, and Windows.