xxHash

xxHash is a family of non-cryptographic hash functions designed for high speed on modern hardware. Created by Yann Collet, xxHash aims for fast data checksums and lightweight code size. The project provides several variants with different output sizes, the most common being XXH32 and XXH64. In addition, newer iterations under the XXH3 family, such as XXH3_64bits and XXH3_128bits, offer improved performance and diffusion on contemporary CPUs.

xxHash is designed to be simple to implement and to support streaming input. It processes data in blocks, uses a small internal state, and relies on fast arithmetic operations and bit rotations to mix input bits. The API typically includes a one-shot function that hashes a complete input and a streaming interface that allows incremental updates, making it suitable for large data streams or progressive hashing.

The software is released under a BSD-style license, which facilitates its adoption in both open-source and commercial projects. It is widely used as a fast non-cryptographic checksum and for indexing data in memory and on disk, as a content-addressable hash in some systems, and as a general-purpose hash for hash tables, deduplication, and similar tasks.

Because xxHash is non-cryptographic, it is not intended for security-sensitive uses. It does not provide the collision resistance or preimage guarantees required for cryptographic applications, such as password hashing or digital signatures. For security needs, cryptographic hash functions should be used instead. The library is implemented in C and has ports or bindings to numerous programming languages.