claude-sdk-rs 2.0.0

A lean async Rust SDK that runs Claude Code as a subprocess on a flat-rate subscription (not metered API credits).
Documentation

claude-sdk-rs

Crates.io docs.rs

A lean async Rust SDK that runs the Claude Code CLI as a subprocess, authenticated through a flat-rate Claude subscription rather than metered API credits. If you already pay for Claude Code, this crate lets you call it programmatically from Rust without a separate API key or per-token billing.

2.0.0 is a ground-up rewrite of the claude-sdk-rs 1.x line, with no migration path. See CHANGELOG.md for what changed and why. If you depend on 1.x, pin claude-sdk-rs = "=1.0.2" — that version is frozen on the legacy-v1 branch.

Why a subprocess wrapper instead of an HTTP client

  • Subscription auth, not metered API keys. Every call rides your existing Claude Code login — no separate API billing to configure or reconcile.
  • Schema locked to captured CLI output, not memory. tests/fixtures/ holds real captured CLI responses; tests/parse_schema.rs asserts against them, and an ignored canary test diffs live CLI output against the fixtures on demand — so a CLI schema change surfaces as a failing test, not silent drift in production.

Prerequisites

  • Rust 1.78+ (via rustup)
  • The claude CLI installed and logged in (claude auth login), on PATH or pointed to via the CLAUDE_BINARY env var
  • A Claude subscription (Pro/Max) — this crate does not use API keys

Quickstart

cargo add claude-sdk-rs

use claude_sdk_rs::{execute, Config};

#[tokio::main]
async fn main() -> claude_sdk_rs::Result<()> {
    let config = Config::default();
    let outcome = execute(&config, "What is 2 + 2?").await?;
    println!("{}", outcome.text);
    Ok(())
}

How it works

There is no HTTP client here. execute() spawns the claude binary as a subprocess (tokio::process::Command, .kill_on_drop(true), wrapped in a single whole-call timeout), passes your prompt and options as CLI flags, and parses the CLI's --output-format json response into a typed Outcome. Authentication is whatever the claude CLI itself is already using — your Claude subscription login, sourced from the macOS Keychain or ~/.claude/.credentials.json.

Config also covers system_prompt, model, allowed_tools/disallowed_tools, continue_session/resume (multi-turn), json_schema (structured output), isolated (credential isolation for concurrent callers), and timeout (per-call override of the 300s default). See docs.rs for the full API.

Platform note: the built-in credential isolation (Config.isolated) sources credentials via the macOS Keychain with a file fallback. It has only been exercised on macOS; other platforms may need the file-based fallback path exclusively.

Tests

cargo test

License

Licensed under either of

at your option. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Built for one operator and released because it may be useful to others — there is no support obligation, no issue-response SLA, and no stability promise.