Alejandra 🔜 Rust Week 2026

I'm mapping ALL crates.io and their dependencies.

These are just 14341 crates (palindrome number and about 5.9% of crates.io) and it already seems something of cosmical proportions. Like some sort of megastructure. And we have some data!

Out of 14341 crates, 46% depend directly on tokio, 4.8% depend directly on syn, only 44 depend on a rustc_* internal crate, almost all of them being rustc_version and even being the most downloaded crate of all crates.io, only 166 depend on `hashbrown`.

#rust #opensource #foss

Mar 18 at 11:10pmWeb
Show threadAlejandra 🔜 Rust Week 2026Mar 18

Fun facts about the graph:

There are 615 crates without any dependencies, those can be seen on up right.

Down right, with a big red cloud are AWS Rust crates, which ALL depend on `tokio` but not `syn`, `clap` or `hashbrown`. Curious.

On cyan to its side, Google crates.

Here is the color code:
Yellow - Syn
Light green - Clap
Not so light green - Rand
Red - Tokio

Tokio is put last because if it's first, maybe 70% of that big cloud is red and that's not interesting.

Show threadMikalaiMar 19
@blyxyas
Only 46% depend on tokio?
Show threadAlejandra 🔜 Rust Week 2026Mar 19
@mikalai 46% directly depend on tokio (as in it's directly depended on in Cargo.toml). I still have to do some processing, but I imagine that much more indirectly depend on it.
Show threadTed MielczarekMar 19
@mikalai @blyxyas I'm actually surprised it's that high. Tokio seems to most often be used as a dependency by applications, not libraries. If you don't need async file I/O or task scheduling you can write async code in a library using just std::future.
Show threadAlejandra 🔜 Rust Week 2026Mar 19
@tedmielczarek @mikalai This 14K crates are the most recently updated ones (so, the ones that have updated in the last ~50 days). So that might skew up some results (maybe these last two months there have been more binaries updated on crates.io).
Show threadGunnlaugur Þór BriemMar 21
@tedmielczarek @mikalai @blyxyas if I were writing such a library (which I'm not, so ignoramus here), I would likely make some integration tests, and wouldn't those use tokio?
Show threadTed MielczarekMar 21

@gthb @mikalai @blyxyas you'd list tokio in dev-dependencies in that case: https://doc.rust-lang.org/rust-by-example/testing/dev_dependencies.html

I don't know the exact methodology used to generate the graph but it seems reasonable to treat dependencies and dev-dependencies separately.

Dev-dependencies - Rust By Example

Rust by Example (RBE) is a collection of runnable examples that illustrate various Rust concepts and standard libraries.

Show threadGunnlaugur Þór BriemMar 21
@tedmielczarek @mikalai @blyxyas right, I was assuming dev-deps were included, but no reason to assume that. And I bet the difference is interesting in its own right!
Show threadJacob PrattMar 19
@blyxyas How does this take into account optional features? Tons of crates (like my `time`) depend on `serde` and `rand`, but it's entirely opt-in.
Show threadAlejandra 🔜 Rust Week 2026Mar 19
@jhpratt They are still taken into account as dependencies, maybe the links between these could have less opacity, but it wouldn't be noticeable at full scale.
Show threadThankful MachineMar 19
@blyxyas Looks delicious
Show threadMikalaiMar 22
@blyxyas
Question.
Is it possible, in Rust, to just use type definitions without any code being used, like when type is used? Are there situations like it?
This question is induced by "import type" mechanics in TypeScript. But, does low-level language always have code to add?
Show threadAlejandra 🔜 Rust Week 2026Mar 22

@mikalai I guess it's possible, but if only type definitions are used, everything will be ran at compiletime and thus no output will be user-visible.

I've seen someone run factorio just with Rust types, so everything is possible in the weird realm of type theory

Show threadMikalaiMar 22
@blyxyas
... beloved realm of types ... usage in practice