HTTP Client with reqwest

Use case

You need to call external APIs: GET/POST, headers, JSON body and response. reqwest is the standard async HTTP client; it integrates with serde for JSON and tokio for async.

In C#: Like HttpClient: GetAsync, PostAsync, ReadFromJsonAsync. In Rust, reqwest is async and returns Result; use .await? and optional .json::<T>().

GET request

Create a client (or use reqwest::get(url) for one-off calls), then .await the response. Use .text().await for body as string or .json::<T>().await to deserialize.

let client = reqwest::Client::new();
let res = client.get("https://httpbin.org/get").send().await?;
let status = res.status();
let body = res.text().await?;

In C#: Like await client.GetAsync(url) and await response.Content.ReadAsStringAsync().

POST with JSON

Use .json(&payload) to set the body and Content-Type. Use .json::<T>() on the response to deserialize.

#[derive(serde::Serialize)]
struct Payload { name: String }

let payload = Payload { name: "Rust".into() };
let res = client.post("https://httpbin.org/post")
    .json(&payload)
    .send()
    .await?;
let json: serde_json::Value = res.json().await?;

In C#: Like PostAsJsonAsync(url, payload) and ReadFromJsonAsync<T>().

Error handling

reqwest returns Result; use ? in an async function or match. Status errors (4xx, 5xx) do not automatically turn into Err—check res.status().is_success() or use res.error_for_status() to convert non-2xx into an error.

In C#: Like checking response.IsSuccessStatusCode or throwing on failure.

Key takeaway

Use reqwest::Client::new() (or reqwest::get for simple GET). Chain .get(url)/.post(url), .json(&body) for JSON, .send().await?, then .text().await or .json::<T>().await. Run with #[tokio::main] and handle Result.