Introduction

The standard Rust project structure is defined by Cargo, Rust’s build system and package manager.

  1. To create a new project run cargo new <project name>
  2. This creates a conventional project layout that the Rust community follows almost universally.

Standard Rust Project Structure (for a binary crate)

my_project/
├── Cargo.toml          # Project metadata, dependencies, etc.
├── Cargo.lock          # Locked dependency versions (commit for apps, ignore for libs)
├── src/
│   ├── main.rs         # Entry point for binary crates
│   └── lib.rs          # (only for library crates or binaries with lib)
├── tests/              # Integration tests (optional but recommended)
│   └── integration.rs
├── examples/           # Example programs (optional)
│   └── example.rs
├── benches/            # Benchmarks (optional)
│   └── benchmark.rs
└── README.md           # Project documentation

For a Library Crate (cargo new my_lib --lib)

my_lib/
├── Cargo.toml
├── src/
│   └── lib.rs          # Public API surface
└── tests/              # Integration tests

1. Use src/bin/ for multiple binaries

src/
├── lib.rs
├── main.rs             # Default binary
└── bin/
    ├── cli.rs          # `cargo run --bin cli`
    └── server.rs

2. Organize large projects with modules

src/
├── main.rs
├── lib.rs
├── models/
│   ├── user.rs
│   └── post.rs
├── services/
│   └── auth.rs
└── utils/
    └── helpers.rs

Use mod declarations in lib.rs or main.rs:

// lib.rs or main.rs
mod models;
mod services;
mod utils;

3. Keep main.rs thin

// main.rs
fn main() {
    my_project::run();
}

// lib.rs
pub fn run() {
    // actual logic
}

4. Use tests/ for integration tests

// tests/integration.rs
use my_project;

#[test]
fn it_works() {
    assert_eq!(my_project::add(2, 2), 4);
}

5. Use examples/ for usage demos

cargo run --example hello

6. Add common config files

├── .gitignore
├── rustfmt.toml        # Code formatting
├── clippy.toml         # Linter config
└── deny.toml           # Cargo-deny for security

Example: Well-Structured App

my_app/
├── Cargo.toml
├── src/
│   ├── main.rs
│   ├── lib.rs
│   ├── config/
│   │   └── mod.rs
│   ├── handlers/
│   │   └── mod.rs
│   └── models/
│       ├── mod.rs
│       └── user.rs
├── tests/
│   └── api_tests.rs
├── examples/
│   └── quickstart.rs
└── README.md

Official Resources

Summary: Follow Cargo Conventions

File/Dir Purpose
Cargo.toml Config & dependencies
src/main.rs Binary entry
src/lib.rs Library entry
src/bin/ Multiple binaries
tests/ Integration tests
examples/ Example code
benches/ Benchmarks

Stick to this structure — it’s what tools, IDEs, and the community expect.

By following this convention, tools like rust-analyzer and Cargo guide you and work best with the standard layout.

Find me on Twitter/ where I tweet about interesting topics on software development.