zzuf

zzuf is a transparent application input fuzzer. It works by intercepting file and network operations of a program and changing random bits in its input, without any change to the program itself.

Its behaviour is deterministic, which makes bugs easy to reproduce: the same seed and ratio of fuzzed bits always produce the same input. zzuf runs a command, such as a media player or an image viewer, against a set of input files, detects crashes, hangs and excessive memory use, and can test ranges of seeds automatically. A manual page documents its options.

zzuf is free and open source under the WTFPL licence. Its source code has not changed since 2022.