https://crates.io/crates/httparse is a widely used HTTP parsing crate, most notably powering hyper and reqwest.

cargo-geiger shows the following when httparse is used via reqwest:

Functions  Expressions  Impls  Traits  Methods  Dependency
10/10      198/232      0/0    0/0     3/3      httparse 1.3.5

Unsafe code in parsers it quite dangerous. Binary format parsers are the poster children for memory safety vulnerabilities.

Text format parsers are a bit less dangerous, but having so much unsafe parsing code exposed to untrusted input is still scary.