Feature flags
The alloy meta-crate uses feature flags to expose focused crates and select implementations. Start
with the default features for a typical HTTP application, then add only the capabilities your code
uses.
The exact feature graph can change between releases. For the version in your Cargo.lock, verify
the docs.rs feature list or the
alloy Cargo manifest.
Recommended starting points
Default: HTTP application
alloy = "2.1.1"The defaults enable std, the Reqwest HTTP client with rustls, Alloy Core defaults, and
essentials. The essentials group includes contracts, an HTTP provider, standard Ethereum RPC
types, and local signers.
Broad application support
alloy = { version = "2.1.1", features = ["full"] }full adds commonly used consensus and EIP types, WebSocket and IPC providers, pubsub, KZG, RLP,
and the trace, txpool, debug, and Anvil RPC APIs. Despite its name, it is not every optional
integration: node binaries, cloud and hardware signers, and several RPC namespaces remain opt-in.
No default features
alloy = { version = "2.1.1", default-features = false, features = ["sol-types"] }Use this pattern only when you intend to assemble a minimal surface. Disabling defaults removes the
HTTP provider, contracts, local signer, and std choices supplied by the default set. Feature
requirements are additive, so compile every intended target after changing them.
Task-to-feature map
| Capability | Feature(s) to consider | Notes |
|---|---|---|
| HTTP provider | provider-http | Included by essentials and the defaults |
| WebSocket provider and subscriptions | provider-ws | Enables pubsub and the default WebSocket TLS backend |
| WebSocket with ring or native TLS | provider-ws-ring, provider-ws-native-tls | Choose the backend required by your platform |
| IPC provider | provider-ipc | Enables pubsub |
| Contract calls and bindings | contract | Pulls in providers and ABI features |
| Local private keys | signer-local | Included by essentials |
| Mnemonics or keystores | signer-mnemonic, signer-keystore | Add to signer-local behavior |
| AWS KMS, GCP KMS, or Turnkey | signer-aws, signer-gcp, signer-turnkey | Each integration is independent |
| Ledger or Trezor | signer-ledger, signer-trezor | Ledger also has browser and Node variants |
| Anvil process helpers | provider-anvil-node | Includes provider Anvil RPC and node bindings; not in full |
| Standalone node bindings | node-bindings | Re-exports process bindings without provider helpers |
debug_* RPC methods | provider-debug-api | Also enables debug and trace RPC types |
trace_* RPC methods | provider-trace-api | Enables trace RPC types |
txpool_* RPC methods | provider-txpool-api | Enables txpool RPC types |
| Admin, Engine, MEV, or Net methods | provider-admin-api, provider-engine-api, provider-mev-api, provider-net-api | These namespaces are not included as a group by full |
| Rate-limited transport | transport-throttle | Low-level transport capability |
| Dynamic or JSON ABI | dyn-abi, json-abi | contract already enables both |
| EIP-712 signing | eip712 | Enables support across compatible configured signers |
HTTP implementation and TLS
The defaults select Reqwest with rustls. Advanced users can choose from reqwest-rustls-tls,
reqwest-native-tls, reqwest-default-tls, or the hyper HTTP implementation. Disable default
features before replacing the default combination, and test the target platforms you support.
WebSocket TLS choices are expressed through the provider features listed above. Avoid enabling multiple TLS backends unless a dependency requires them.
std, WebAssembly, and no_std
The networking-focused meta-crate is designed primarily for std. The wasm-bindgen feature adapts
supported transport behavior for WebAssembly; it does not make every Alloy crate available in every
browser environment.
For a no_std or otherwise constrained library, depend directly on the core or protocol crate you
need, disable its default features, and verify its own feature list. Do not assume that disabling
std on the alloy meta-crate makes provider, signer, or transport integrations no_std.
Diagnose a missing feature
If an import or method is unavailable:
- Open the item on docs.rs and check its Available on crate feature annotation.
- Inspect
cargo tree -e features -i alloyto see which features are active. - Add the smallest owning feature and run
cargo check --all-targets. - If the item belongs to an individual crate, check that crate's features rather than assuming the meta-crate uses the same flag name.