Originally published at claudeguide.io/claude-api-rust-guide

Claude API with Rust: Complete reqwest Tutorial and Integration Guide

Rust has no official Anthropic SDK, but integrating the Claude API in Rust is straightforward using reqwest and serde_json. You send a POST to https://api.anthropic.com/v1/messages with your API key, model, and messages array — and parse the JSON response. This guide covers sync and async patterns, streaming, structured errors, and production-ready patterns for Rust applications in 2026.

As of April 2026, Anthropic does not maintain a first-party Rust crate. The community workaround — reqwest + serde — is idiomatic, stable, and sufficient for production workloads.

Project Setup

# Cargo.toml
[dependencies]
reqwest = { version = "0.12", features = ["json"] }
tokio = { version = "1", features = ["full"] }
serde = { version = "1", features = ["derive"] }
serde_json = "1"
anyhow = "1"
dotenvy = "0.15"

cargo new claude-rust-demo
cd claude-rust-demo

Basic Message Request

use reqwest::Client;
use serde::{Deserialize, Serialize};
use std::env;

#[derive(Serialize)]
struct Message {
    role: String,
    content: String,
}

#[derive(Serialize)]
struct ClaudeRequest {
    model: String,
    max_tokens: u32,
    messages: Vec<Message

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---

## Streaming Responses

For long outputs, streaming returns tokens as they are generated:

rust
use reqwest::Client;
use futures_util::StreamExt;

async fn stream_claude(api_key: &str, prompt: &str) -

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