What Are Dev Dependencies in Rust?

Dev dependencies in Rust are external crates listed in the [dev-dependencies] section of your Cargo.toml file that are only included when running tests or building documentation, not when compiling your final release binary. They allow you to use testing frameworks like rand or tokio without bloating your production build.

[dev-dependencies]
rand = "0.8.5"

To add a dev dependency, run:

cargo add --dev rand

Dev dependencies are tools you only need while building or testing your software, not when users run it. Think of them like a carpenter's saw and hammer: essential for construction, but you don't ship them with the finished table.