Cargo comes with quite a lot of nifty things pre-packaged, like fmt, clippy and so on. But there are a lot of addons out there, and it is a bit hard to discover these, so I thought it would be interesting to hear what everybody is using.
The things I have installed is:
cargo-outdated - Find outdated dependencies
cargo-udeps - Find unused dependencies
cargo-flamegraph - Performance analysis
cargo-about - I use it to list licenses
Of these, it is cargo-outdated I use frequently. So, what is your cargo addon you cannot live without.
cargo-audit is great for keeping an eye on what dependencies have known vulnerabilities and need upgrading. Not something I use for every side project, but is used frequently on the systems we have running at work.
Instead of cargo addons I mostly use this neovim plugin: https://github.com/Saecki/crates.nvim. I can add a dependency by typing it in Cargo.toml, and it shows me the latest version number, and tells me whether I guessed wrong about dashes vs underscores in the package name. It shows virtual text next to crates that have upgrades available. It has commands for upgrading the crate under the cursor, or all crates. It has an interactive feature selector.
What I could still use is cargo-udeps. I'll check that one out!