Ashampoo ZIP Pro vs Zstandard

Ashampoo ZIP Pro has no write-up on Specifiction yet; its figures are above.

Zstandard is a lossless compression algorithm for real-time workloads, with controls that let users shift compression speed and ratio in small increments. Its reference implementation includes a C library and a command-line utility that creates and decodes .zst, .gz, .xz, and .lz4 files. The format is stable and documented in RFC 8878; the implementation is available under BSD or GPLv2. For small, related samples, training can produce a data-specific dictionary to improve compression. The same dictionary must be present for both compression and decompression, and the samples need to be correlated; there is no universal dictionary. The project documents builds with Make, CMake, Meson, Visual Studio, Buck, and Bazel, plus installation using vcpkg and Conan. Community bindings and ports are listed for languages including Python, Rust, Java, C#, JavaScript, Go, PHP, and Swift. Zstandard is free, with a free plan, and supports Linux, Windows, and macOS.