In this tool demonstration paper, we propose a tool named Fuzz4B (Fuzzing for Beginner), which is a front-end to a representative fuzzer AFL for developers who are inexperienced in fuzz testing. Fuzz4B is not only a front-end, but it also allows developers to reproduce a crash and minimize a fuzz that causes the crash. As a usage example, we demonstrated the use of Fuzz4B to perform fuzz testing to discover a failure of an open source library librope. Fuzz4B and its video are available at: https://github.com/Ryu-Miyaki/Fuzz4B.