Throughout this book, we pull in quite a few crates. If you ever find yourself thinking “wait, which crate was that again?”, this is the page to come back to. I’ve organized everything by concern so you can quickly find what you need and understand why it’s in our stack.
Crate Purpose Notes
axum HTTP routing, extractors, and handler framework The foundation. Use with the macros feature for #[debug_handler]. tokio Async runtime Use features = ["full"] unless you need to minimize dependencies. tower Middleware abstractions and utilities Provides ServiceBuilder, ServiceExt (for oneshot in tests), and composable layers. tower-http HTTP-specific middleware CORS, compression, tracing, timeouts, request IDs, body limits, and more. Enable features selectively. hyper HTTP implementation You’ll rarely interact with hyper directly when using Axum, but it’s the HTTP engine under the hood.
Crate Purpose Notes
serde Serialization framework Use features = ["derive"] for #[derive(Serialize, Deserialize)]. serde_json JSON serialization Axum’s Json extractor uses this under the hood. uuid UUID generation and parsing Use features = ["v4", "serde"] for random UUIDs with serde support. chrono Date and time handling Use features = ["serde"] for serialization. Prefer DateTime<Utc> for timestamps.
Crate Purpose Notes
sqlx Async SQL with compile-time checking Our go-to for most Axum projects. Supports PostgreSQL, MySQL, and SQLite. diesel Type-safe ORM and query builder Mature and well-tested. Use diesel-async for async support. sea-orm ActiveRecord-style async ORM Worth considering if raw SQL feels like too much ceremony for your use case. axum-sqlx-tx Request-scoped SQLx transactions Begins a transaction for each request automatically, then commits or rolls back based on the response status.
Crate Purpose Notes
thiserror Derive macros for custom error types We use this for domain errors and our AppError enum where we need to match on variants. anyhow Flexible error type with context chaining Great for the catch-all Internal variant and in infrastructure code. Don’t be shy with .context().
Crate Purpose Notes
validator Derive-based input validation Supports email, url, length, range, and custom validators. garde Alternative validation with const generics A newer take on validator with a different API style. axum-valid Pre-built validated extractors for Axum Integrates with validator, garde, and validify. Saves you from writing your own extractors.
Crate Purpose Notes
jsonwebtoken JWT encoding and decoding The go-to for JWT-based auth in Rust. argon2 Password hashing What I’d recommend for password hashing today. Prefer it over bcrypt for new projects. axum-login Session-based authentication A good fit for traditional web apps with server-side sessions. axum-csrf-sync-pattern CSRF protection Implements the OWASP Synchronizer Token Pattern. tower-governor Rate limiting Per-IP rate limiting using the governor algorithm. tower-sessions Session middleware Server-side session management with pluggable backends.
Crate Purpose Notes
config Layered configuration loading Supports files, environment variables, and multiple formats. dotenvy Load .env files Fork of the original dotenv crate. Call .ok() instead of .unwrap() so it doesn’t blow up in production. secrecy Sensitive value protection Wrap secrets in SecretString. It’ll redact them in debug output and zero memory on drop.
Crate Purpose Notes
tracing Structured logging and spans If you’re doing structured logging in Rust, this is what everyone reaches for. tracing-subscriber Tracing output configuration Use features = ["env-filter", "json"] for environment-based filtering and JSON output. tracing-opentelemetry Bridge tracing to OpenTelemetry Converts tracing spans into OpenTelemetry spans for distributed tracing. opentelemetry OpenTelemetry API Core API for distributed tracing and metrics. opentelemetry-otlp OTLP exporter Exports traces to Jaeger, Tempo, Datadog, and other OTLP-compatible backends. axum-tracing-opentelemetry Axum OpenTelemetry integration Automatic trace context propagation for Axum.
Crate Purpose Notes
utoipa Compile-time OpenAPI spec generation Generates OpenAPI 3.0 specs from code annotations. utoipa-swagger-ui Swagger UI for utoipa Serves an interactive API documentation UI at a configurable path.
Crate Purpose Notes
tower (ServiceExt) Integration testing without a server Use oneshot() to send requests through the router directly. mockall Automatic mock generation Generates mock implementations of your traits for unit testing. axum-test Testing library for Axum Gives you a TestClient with a nicer API than raw oneshot.
Crate Purpose Notes
reqwest Async HTTP client The HTTP client you’ll see in most Rust projects. Async-native with connection pooling.
Crate Purpose Notes
tonic gRPC framework Native async gRPC client and server. Integrates with Tower middleware. tonic-prost Tonic + Prost runtime Runtime support for tonic services using prost-generated types. prost Protocol Buffers Protobuf serialization/deserialization. Used by tonic for message types. tonic-prost-build Proto code generation Compiles .proto files into Rust code at build time. Goes in [build-dependencies]. This replaced direct tonic-build usage as of tonic 0.14. tonic-reflection gRPC server reflection Lets grpcurl and other tools discover your service’s API.
Crate Purpose Notes
tokio-util Extended Tokio utilities Provides CancellationToken for structured shutdown, plus codecs and other helpers. futures Future combinators Provides FuturesUnordered, StreamExt, and other utilities for working with async streams.
Crate Purpose Notes
apalis Background task processing Type-safe, extensible, supports PostgreSQL/Redis/SQLite backends. Built-in monitoring and graceful shutdown. fang Persistent job queue Workers in separate Tokio tasks with auto-restart on panic. Cron scheduling and retry backoff. backie Async task queue PostgreSQL-backed, designed for horizontal scaling across multiple processes.