.zst File — Zstandard Compressed File

ZST files use Zstandard (zstd) compression, a modern algorithm developed by Yann Collet at Facebook (Meta) in 2015. Zstandard is designed to provide compression ratios comparable to gzip's maximum level while operating at speeds closer to LZ4 — effectively bridging the gap between fast and high-ratio compressors. At its fastest settings, zstd compresses and decompresses significantly faster than gzip while achieving similar ratios; at maximum compression, it approaches LZMA/XZ ratios with much faster decompression. The algorithm supports 22 compression levels plus ultra settings, dictionary compression for small data, and efficient multi-threaded operation. Zstandard has been rapidly adopted across the industry — it's used by Facebook for data storage, by the Linux kernel for BTRFS filesystem compression, by package managers (Arch Linux, Fedora), by databases (RocksDB, MySQL), and by HTTP content encoding (RFC 8878). The format includes frame-based structure with checksums, skippable frames for metadata, and dictionary IDs. Zstandard represents the current state of the art in general-purpose compression, offering the best speed-to-ratio tradeoff available.