How do I remove unused dependencies in Cargo.toml?

Question

How do I find out the dependencies in Cargo.toml that are unused? How can I remove them automatically?

Answer 1

Update for 2024

As of Sep 2024, this answer requires nightly to run. If you don't want nightly builds, refer to Michael Hall's or Mujeeb Kalwar's answer instead.

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One option is to use cargo-udeps.

You can install it via command:

cargo install cargo-udeps --locked

Then, to find unused dependencies in production target:

cargo +nightly udeps

To find unused dev dependencies:

cargo +nightly udeps --all-targets