anthropic-rs-sdk

Status: v0.1 — non-streaming Messages API only. This crate is an early port of the official Anthropic Go SDK to Rust. See ROADMAP.md for the full feature checklist.

Async Rust SDK for the Anthropic API. Built on reqwest + tokio, with a typed request/response model, forward-compatible enums, redacted credentials, and wiremock-driven tests so CI never touches the real API.

[dependencies]
anthropic-rs-sdk = "0.1"
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

The library name is anthropic, so use anthropic::Client works regardless of the crate name on crates.io.

Quickstart

use anthropic::types::{InputMessage, MessageCreateParams, model};

#[tokio::main]
async fn main() -> anthropic::Result<()> {
    // Reads ANTHROPIC_API_KEY (and optional ANTHROPIC_BASE_URL).
    let client = anthropic::Client::from_env()?;

    let response = client
        .messages()
        .create(
            MessageCreateParams::builder()
                .model(model::CLAUDE_HAIKU_4_5)
                .max_tokens(256)
                .messages(vec![InputMessage::user("Hello, Claude!")])
                .build(),
        )
        .await?;

    println!("{}", response.text());
    Ok(())
}

Run the bundled examples:

ANTHROPIC_API_KEY=sk-ant-... cargo run --example basic_message
ANTHROPIC_API_KEY=sk-ant-... cargo run --example multi_turn

What's in v0.1

Client::from_env() — reads ANTHROPIC_API_KEY (+ optional ANTHROPIC_BASE_URL)
Client::builder() — explicit api_key, base_url, timeout, http_client
messages.create — non-streaming, with multi-turn Vec<InputMessage>
Model constants for the current Claude family (Opus 4.7, Sonnet 4.6, Haiku 4.5, plus dated variants and the older 4.x line)
Model::custom("...") escape hatch for unknown IDs
Typed Error with Error::Api { status, error_type, message, request_id, raw }
request-id preserved on every error response
secrecy::SecretString-wrapped API key with redacted Debug
21 tests passing — 14 serde round-trips, 4 wiremock end-to-end, 3 doctests
Live-API integration test gated by --features live-tests

What's not in v0.1

Streaming, tool use, multimodal (image / PDF), files, message batches, the beta surface (agents / sessions / memory / skills / vault / user profiles), Bedrock + Vertex providers, retries with backoff. Each of these has a tracked checkbox in ROADMAP.md — the goal is full Go SDK parity by v1.0.

Cargo features

Feature	Default	Effect
`rustls-tls`	yes	TLS via `rustls`. Pure Rust, easy cross-compile.
`native-tls`	no	TLS via the OS trust store. Mutually exclusive with above.
`streaming`	no	(Reserved) SSE streaming support. Lands in v0.2.
`tools`	no	(Reserved) Tool-use helpers. Lands in v0.2.
`bedrock`	no	(Reserved) AWS Bedrock provider. Lands in v0.4.
`vertex`	no	(Reserved) Google Vertex AI provider. Lands in v0.4.
`live-tests`	no	Enables `tests/messages_live.rs` against the real API.

Verification

cargo fmt --all --check
cargo clippy --all-targets --all-features -- -D warnings
cargo test                                # no network, no API key
RUSTDOCFLAGS="-D warnings" cargo doc --no-deps --all-features
ANTHROPIC_API_KEY=sk-ant-... cargo test --features live-tests

Project conventions

Contributor-facing conventions live in CLAUDE.md: error handling, async rules, secrets handling, testing strategy, dependency hygiene.

License

MIT — see LICENSE.

Why "anthropic-rs-sdk"?

anthropic, anthropic-sdk, and anthropic-rs were all taken on crates.io by stale community crates last updated in 2024 (none of which support the Claude 4 family). anthropic-rs-sdk keeps the convention close to anthropic-sdk-go while making it obvious this is the Rust port.

anthropic-rs-sdk 0.1.0