diff --git a/Cargo.lock b/Cargo.lock
index 2ae16d7b..e1124403 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1325,6 +1325,7 @@ name = "impit-node"
 version = "0.0.0"
 dependencies = [
  "bytes",
+ "futures-util",
  "h2",
  "impit",
  "napi",
diff --git a/impit-node/Cargo.toml b/impit-node/Cargo.toml
index 26c57945..8df73f1f 100644
--- a/impit-node/Cargo.toml
+++ b/impit-node/Cargo.toml
@@ -16,6 +16,7 @@ h2 = "0.4.7"
 reqwest = { version="0.13.1" }
 tokio-stream = "0.1.17"
 bytes = "1.11.1"
+futures-util = "0.3"
 
 [build-dependencies]
 napi-build = "2.3.2"
diff --git a/impit-node/index.wrapper.js b/impit-node/index.wrapper.js
index 3e9ed22e..91b74fd4 100644
--- a/impit-node/index.wrapper.js
+++ b/impit-node/index.wrapper.js
@@ -49,15 +49,22 @@ function toUint8Array(chunk) {
     return typeof chunk === 'string' ? new TextEncoder().encode(chunk) : new Uint8Array(chunk);
 }
 
-function concatUint8Arrays(chunks) {
-    const totalLength = chunks.reduce((acc, chunk) => acc + chunk.length, 0);
-    const result = new Uint8Array(totalLength);
-    let offset = 0;
-    for (const chunk of chunks) {
-        result.set(chunk, offset);
-        offset += chunk.length;
-    }
-    return result;
+// Streamed bodies are passed to the native layer as a ReadableStream of bytes, so that the chunks
+// reach the connection as they are produced instead of being buffered before the request starts.
+function toByteStream(source) {
+    const reader = source instanceof ReadableStream ? source.getReader() : source[Symbol.asyncIterator]();
+    const next = reader.read?.bind(reader) ?? reader.next.bind(reader);
+
+    return new ReadableStream({
+        async pull(controller) {
+            const { done, value } = await next();
+            if (done) {
+                controller.close();
+            } else {
+                controller.enqueue(toUint8Array(value));
+            }
+        },
+    });
 }
 
 function shouldRewriteRedirectToGet(httpStatus, method) {
@@ -193,23 +200,9 @@ class Impit extends native.Impit {
             return { body: new Uint8Array(await body.arrayBuffer()), type: body.type };
         } else if (body instanceof FormData) {
             return await this.#generateMultipartFormData(body);
-        } else if (body instanceof ReadableStream) {
-            const reader = body.getReader();
-            const chunks = [];
-            let done = false;
-            while (!done) {
-                const { done: streamDone, value } = await reader.read();
-                done = streamDone;
-                if (value != null) chunks.push(toUint8Array(value));
-            }
-            return { body: concatUint8Arrays(chunks), type: '' };
-        } else if (body && typeof body[Symbol.asyncIterator] === 'function') {
-            // Node.js streams (e.g. Readable.from(...)) and other async iterables.
-            const chunks = [];
-            for await (const chunk of body) {
-                chunks.push(toUint8Array(chunk));
-            }
-            return { body: concatUint8Arrays(chunks), type: '' };
+        } else if (body instanceof ReadableStream || typeof body[Symbol.asyncIterator] === 'function') {
+            // Web streams, Node.js streams (e.g. Readable.from(...)) and other async iterables.
+            return { bodyStream: toByteStream(body), type: '' };
         }
         return { body, type: '' };
     }
@@ -238,8 +231,9 @@ class Impit extends native.Impit {
         options.headers = canonicalizeHeaders(options?.headers);
 
         if (options?.body) {
-            const { body: requestBody, type } = await this.#serializeBody(options.body);
+            const { body: requestBody, bodyStream, type } = await this.#serializeBody(options.body);
             options.body = requestBody;
+            options.bodyStream = bodyStream;
             if (type && !options.headers.some(([key]) => key.toLowerCase() === 'content-type')) {
                 options.headers.push(['Content-Type', type]);
             }
@@ -252,6 +246,7 @@ class Impit extends native.Impit {
             method: options.method,
             headers: options.headers,
             body: options.body,
+            bodyStream: options.bodyStream,
             timeout: options.timeout,
             forceHttp3: options.forceHttp3,
             signal: options.signal,
@@ -316,6 +311,7 @@ class Impit extends native.Impit {
                 method,
                 headers,
                 body: method === 'GET' ? undefined : options.body,
+                bodyStream: method === 'GET' ? undefined : options.bodyStream,
             });
 
             const originalResponse = await Promise.race([
@@ -349,6 +345,10 @@ class Impit extends native.Impit {
                     url = new URL(location, url).toString();
                     method = shouldRewriteRedirectToGet(originalResponse.status, method) ? 'GET' : method;
 
+                    if (options.bodyStream && method !== 'GET') {
+                        throw new TypeError(`Cannot follow a redirect that resends a streaming request body: ${url}`);
+                    }
+
                     continue;
                 }
             }
diff --git a/impit-node/src/lib.rs b/impit-node/src/lib.rs
index 90ec326d..269694ba 100644
--- a/impit-node/src/lib.rs
+++ b/impit-node/src/lib.rs
@@ -1,6 +1,10 @@
 use std::time::Duration;
 
-use impit::{errors::ImpitError, impit::Impit, request::RequestOptions};
+use impit::{
+  errors::ImpitError,
+  impit::Impit,
+  request::{ImpitBody, RequestOptions},
+};
 use napi::{bindgen_prelude::ObjectFinalize, Env};
 use napi_derive::napi;
 
@@ -136,9 +140,10 @@ impl ImpitWrapper {
       .as_ref()
       .and_then(|init| init.method.to_owned())
       .unwrap_or_default();
-    let body = request_init
-      .and_then(|init| init.body)
-      .map(|array| array.to_vec().into());
+    let body = request_init.and_then(|init| match (init.body, init.body_stream) {
+      (_, Some(stream)) => Some(ImpitBody::from_stream(stream.into_bytes())),
+      (bytes, None) => bytes.map(|array| array.to_vec().into()),
+    });
 
     let response = if matches!(method, HttpMethod::Get | HttpMethod::Head) && body.is_some() {
       Err(ImpitError::BindingPassthroughError(
diff --git a/impit-node/src/request.rs b/impit-node/src/request.rs
index 59657050..e1a843ab 100644
--- a/impit-node/src/request.rs
+++ b/impit-node/src/request.rs
@@ -1,7 +1,25 @@
-use napi::bindgen_prelude::Uint8Array;
+use bytes::Bytes;
+use futures_util::{Stream, TryStreamExt};
+use napi::bindgen_prelude::{sys, FromNapiValue, ReadableStream, Reader, Uint8Array};
 
 use napi_derive::napi;
 
+/// A JS `ReadableStream` of byte chunks, read chunk by chunk as the request body is sent.
+pub struct BodyStream(Reader<Uint8Array>);
+
+impl FromNapiValue for BodyStream {
+  unsafe fn from_napi_value(env: sys::napi_env, value: sys::napi_value) -> napi::Result<Self> {
+    let stream = unsafe { ReadableStream::<Uint8Array>::from_napi_value(env, value)? };
+    Ok(Self(stream.read()?))
+  }
+}
+
+impl BodyStream {
+  pub fn into_bytes(self) -> impl Stream<Item = napi::Result<Bytes>> {
+    self.0.map_ok(|chunk| Bytes::copy_from_slice(&chunk))
+  }
+}
+
 #[derive(Default, Clone)]
 #[napi(string_enum = "UPPERCASE")]
 pub enum HttpMethod {
@@ -24,7 +42,7 @@ pub enum HttpMethod {
 ///
 /// See {@link Impit.fetch} for usage.
 #[derive(Default)]
-#[napi(object)]
+#[napi(object, object_to_js = false)]
 pub struct RequestInit {
   /// HTTP method to use for the request. Default is `GET`.
   ///
@@ -47,6 +65,9 @@ pub struct RequestInit {
   )]
   /// Request body. Can be a string, Buffer, ArrayBuffer, TypedArray, DataView, Blob, File, URLSearchParams, FormData or ReadableStream.
   pub body: Option<Uint8Array>,
+  /// Set by the JS wrapper instead of `body` when the body is a stream. Takes precedence over `body`.
+  #[napi(skip_typescript)]
+  pub body_stream: Option<BodyStream>,
   /// Request timeout in milliseconds. Overrides the Impit-wide timeout option from {@link ImpitOptions.timeout}.
   pub timeout: Option<u32>,
   /// Force the request to use HTTP/3. If the server doesn't expect HTTP/3 or the Impit instance doesn't have HTTP/3 enabled (via the {@link ImpitOptions.http3} option), the request will fail.
diff --git a/impit-node/test/basics.test.ts b/impit-node/test/basics.test.ts
index f009f8cc..521b38ed 100644
--- a/impit-node/test/basics.test.ts
+++ b/impit-node/test/basics.test.ts
@@ -522,6 +522,20 @@ describe.each([
             expect(json.data).toEqual(STRING_PAYLOAD);
         });
 
+        // https://github.com/apify/impit/issues/513
+        test('streamed bodies are sent chunk by chunk', async () => {
+            const chunks = ['{"Impit-Test":', '"foořžš"}'];
+            const response = await impit.fetch(localPostUrl, {
+                method: HttpMethod.Post,
+                body: Readable.from(chunks) as any,
+            });
+            const json = await response.json();
+
+            expect(json.headers?.['transfer-encoding']).toBe('chunked');
+            expect(json.headers?.['content-length']).toBeUndefined();
+            expect(json.data).toEqual(STRING_PAYLOAD);
+        });
+
         test('Request with body preserves its Content-Type', async () => {
             const request = new Request(localPostUrl, {
                 method: 'POST',
diff --git a/impit-python/python/impit/impit.pyi b/impit-python/python/impit/impit.pyi
index f1667a53..ce39e96d 100644
--- a/impit-python/python/impit/impit.pyi
+++ b/impit-python/python/impit/impit.pyi
@@ -6,7 +6,7 @@ from .headers import Headers
 from . import Browser
 
 from typing import Any
-from collections.abc import Iterator, AsyncIterator
+from collections.abc import AsyncIterable, AsyncIterator, Iterable, Iterator
 from contextlib import AbstractAsyncContextManager, AbstractContextManager
 
 
@@ -518,7 +518,7 @@ class Client:
     def get(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -538,7 +538,7 @@ class Client:
     def post(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -559,7 +559,7 @@ class Client:
     def put(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -579,7 +579,7 @@ class Client:
     def patch(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -599,7 +599,7 @@ class Client:
     def delete(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -619,7 +619,7 @@ class Client:
     def head(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -639,7 +639,7 @@ class Client:
     def options(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -659,7 +659,7 @@ class Client:
     def trace(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -680,7 +680,7 @@ class Client:
         self,
         method: str,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -704,7 +704,7 @@ class Client:
         self,
         method: str,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -859,7 +859,7 @@ class AsyncClient:
     async def get(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -879,7 +879,7 @@ class AsyncClient:
     async def post(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -900,7 +900,7 @@ class AsyncClient:
     async def put(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -920,7 +920,7 @@ class AsyncClient:
     async def patch(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -940,7 +940,7 @@ class AsyncClient:
     async def delete(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -960,7 +960,7 @@ class AsyncClient:
     async def head(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -980,7 +980,7 @@ class AsyncClient:
     async def options(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1000,7 +1000,7 @@ class AsyncClient:
     async def trace(
         self,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1021,7 +1021,7 @@ class AsyncClient:
         self,
         method: str,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1045,7 +1045,7 @@ class AsyncClient:
         self,
         method: str,
         url: str,
-        content: bytes | bytearray | list[int] | None = None,
+        content: bytes | bytearray | list[int] | Iterable[bytes] | AsyncIterable[bytes] | None = None,
         data: dict[str, str] | None = None,
         headers: dict[str, str] | None = None,
         timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1078,7 +1078,7 @@ class AsyncClient:
 def stream(
     method: str,
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1111,7 +1111,7 @@ def stream(
 
 def get(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1144,7 +1144,7 @@ def get(
 
 def post(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1177,7 +1177,7 @@ def post(
 
 def put(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1210,7 +1210,7 @@ def put(
 
 def patch(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1243,7 +1243,7 @@ def patch(
 
 def delete(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1276,7 +1276,7 @@ def delete(
 
 def head(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1309,7 +1309,7 @@ def head(
 
 def options(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
@@ -1339,7 +1339,7 @@ def options(
 
 def trace(
     url: str,
-    content: bytes | bytearray | list[int] | None = None,
+    content: bytes | bytearray | list[int] | Iterable[bytes] | None = None,
     data: dict[str, str] | None = None,
     headers: dict[str, str] | None = None,
     timeout: float | str | None = USE_CLIENT_DEFAULT,
diff --git a/impit-python/src/async_client.rs b/impit-python/src/async_client.rs
index 24f7a6be..646c0903 100644
--- a/impit-python/src/async_client.rs
+++ b/impit-python/src/async_client.rs
@@ -6,12 +6,12 @@ use impit::{
     impit::{Impit, ImpitBuilder},
     request::RequestOptions,
 };
-use pyo3::{exceptions::PyTypeError, ffi::c_str, prelude::*};
+use pyo3::{ffi::c_str, prelude::*};
 
 use crate::{
     cookies::PythonCookieJar,
     errors::ImpitPyError,
-    request::{form_to_bytes, parse_timeout, RequestBody, USE_CLIENT_DEFAULT_SENTINEL},
+    request::{parse_timeout, to_body, RequestBody, USE_CLIENT_DEFAULT_SENTINEL},
     response::ImpitPyResponse,
 };
 
@@ -135,7 +135,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -159,7 +159,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -183,7 +183,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -207,7 +207,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -231,7 +231,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -255,7 +255,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -279,7 +279,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -303,7 +303,7 @@ impl AsyncClient {
         &self,
         py: Python<'python>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -328,7 +328,7 @@ impl AsyncClient {
         py: Python<'python>,
         method: &str,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -374,7 +374,7 @@ impl AsyncClient {
         py: Python<'python>,
         method: &str,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         mut data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -384,25 +384,10 @@ impl AsyncClient {
         let mut headers = headers.clone();
 
         if let Some(content) = content {
-            data = Some(RequestBody::Bytes(content));
+            data = Some(content);
         }
 
-        let body: Vec<u8> = match data {
-            Some(data) => match data {
-                RequestBody::Bytes(bytes) => Ok(bytes),
-                RequestBody::Form(form) => {
-                    headers.get_or_insert_with(HashMap::new).insert(
-                        "Content-Type".to_string(),
-                        "application/x-www-form-urlencoded".to_string(),
-                    );
-                    Ok(form_to_bytes(form))
-                }
-                RequestBody::CatchAll(e) => Err(PyErr::new::<PyTypeError, _>(format!(
-                    "Unsupported data type in request body: {e:#?}"
-                ))),
-            },
-            None => Ok(Vec::new()),
-        }?;
+        let body = to_body(data, &mut headers)?;
 
         let timeout = parse_timeout(timeout)?;
 
@@ -423,14 +408,14 @@ impl AsyncClient {
 
         pyo3_async_runtimes::tokio::future_into_py::<_, ImpitPyResponse>(py, async move {
             let response = match method_str.to_lowercase().as_str() {
-                "get" => impit.get(url, Some(body.into()), Some(options)).await,
-                "post" => impit.post(url, Some(body.into()), Some(options)).await,
-                "patch" => impit.patch(url, Some(body.into()), Some(options)).await,
-                "put" => impit.put(url, Some(body.into()), Some(options)).await,
-                "options" => impit.options(url, Some(body.into()), Some(options)).await,
-                "trace" => impit.trace(url, Some(body.into()), Some(options)).await,
-                "head" => impit.head(url, Some(body.into()), Some(options)).await,
-                "delete" => impit.delete(url, Some(body.into()), Some(options)).await,
+                "get" => impit.get(url, Some(body), Some(options)).await,
+                "post" => impit.post(url, Some(body), Some(options)).await,
+                "patch" => impit.patch(url, Some(body), Some(options)).await,
+                "put" => impit.put(url, Some(body), Some(options)).await,
+                "options" => impit.options(url, Some(body), Some(options)).await,
+                "trace" => impit.trace(url, Some(body), Some(options)).await,
+                "head" => impit.head(url, Some(body), Some(options)).await,
+                "delete" => impit.delete(url, Some(body), Some(options)).await,
                 _ => Err(ImpitError::InvalidMethod(method_str.to_string())),
             };
 
diff --git a/impit-python/src/client.rs b/impit-python/src/client.rs
index 06db785f..e691f93b 100644
--- a/impit-python/src/client.rs
+++ b/impit-python/src/client.rs
@@ -11,7 +11,7 @@ use pyo3::{ffi::c_str, prelude::*};
 use crate::{
     cookies::PythonCookieJar,
     errors::ImpitPyError,
-    request::{form_to_bytes, parse_timeout, RequestBody, USE_CLIENT_DEFAULT_SENTINEL},
+    request::{parse_timeout, to_body, RequestBody, USE_CLIENT_DEFAULT_SENTINEL},
     response::{self, ImpitPyResponse},
 };
 
@@ -132,7 +132,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -156,7 +156,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -180,7 +180,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -204,7 +204,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -228,7 +228,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -252,7 +252,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -276,7 +276,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -300,7 +300,7 @@ impl Client {
         &self,
         py: Python<'_>,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -325,7 +325,7 @@ impl Client {
         py: Python<'python>,
         method: &str,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -371,7 +371,7 @@ impl Client {
         py: Python<'_>,
         method: &str,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         mut data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
@@ -381,25 +381,11 @@ impl Client {
         let mut headers = headers.clone();
 
         if let Some(content) = content {
-            data = Some(RequestBody::Bytes(content));
+            data = Some(content);
         }
 
-        let body: Vec<u8> = match data {
-            Some(data) => match data {
-                RequestBody::Bytes(bytes) => Ok(bytes),
-                RequestBody::Form(form) => {
-                    headers.get_or_insert_with(HashMap::new).insert(
-                        "Content-Type".to_string(),
-                        "application/x-www-form-urlencoded".to_string(),
-                    );
-                    Ok(form_to_bytes(form))
-                }
-                RequestBody::CatchAll(e) => Err(ImpitPyError(ImpitError::BindingPassthroughError(
-                    format!("Unsupported data type: {e:?}").to_string(),
-                ))),
-            },
-            None => Ok(Vec::new()),
-        }?;
+        let body = to_body(data, &mut headers)
+            .map_err(|e| ImpitPyError(ImpitError::BindingPassthroughError(e.to_string())))?;
 
         let timeout = parse_timeout(timeout)
             .map_err(|e| ImpitPyError(ImpitError::BindingPassthroughError(e.to_string())))?;
@@ -417,30 +403,14 @@ impl Client {
         py.detach(|| {
             pyo3_async_runtimes::tokio::get_runtime().block_on(async {
                 let response = match method.to_lowercase().as_str() {
-                    "get" => self.impit.get(url, Some(body.into()), Some(options)).await,
-                    "post" => self.impit.post(url, Some(body.into()), Some(options)).await,
-                    "patch" => {
-                        self.impit
-                            .patch(url, Some(body.into()), Some(options))
-                            .await
-                    }
-                    "put" => self.impit.put(url, Some(body.into()), Some(options)).await,
-                    "options" => {
-                        self.impit
-                            .options(url, Some(body.into()), Some(options))
-                            .await
-                    }
-                    "trace" => {
-                        self.impit
-                            .trace(url, Some(body.into()), Some(options))
-                            .await
-                    }
-                    "head" => self.impit.head(url, Some(body.into()), Some(options)).await,
-                    "delete" => {
-                        self.impit
-                            .delete(url, Some(body.into()), Some(options))
-                            .await
-                    }
+                    "get" => self.impit.get(url, Some(body), Some(options)).await,
+                    "post" => self.impit.post(url, Some(body), Some(options)).await,
+                    "patch" => self.impit.patch(url, Some(body), Some(options)).await,
+                    "put" => self.impit.put(url, Some(body), Some(options)).await,
+                    "options" => self.impit.options(url, Some(body), Some(options)).await,
+                    "trace" => self.impit.trace(url, Some(body), Some(options)).await,
+                    "head" => self.impit.head(url, Some(body), Some(options)).await,
+                    "delete" => self.impit.delete(url, Some(body), Some(options)).await,
                     _ => Err(ImpitError::InvalidMethod(method.to_string())),
                 };
 
diff --git a/impit-python/src/lib.rs b/impit-python/src/lib.rs
index 9e16af38..e6b89936 100644
--- a/impit-python/src/lib.rs
+++ b/impit-python/src/lib.rs
@@ -93,7 +93,7 @@ fn impit(_py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
             fn $name(
                 _py: Python,
                 url: String,
-                content: Option<Vec<u8>>,
+                content: Option<RequestBody>,
                 data: Option<RequestBody>,
                 headers: Option<HashMap<String, String>>,
                 timeout: Option<Either<f64, &str>>,
@@ -122,7 +122,7 @@ fn impit(_py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
         _py: Python<'python>,
         method: &str,
         url: String,
-        content: Option<Vec<u8>>,
+        content: Option<RequestBody>,
         data: Option<RequestBody>,
         headers: Option<HashMap<String, String>>,
         timeout: Option<Either<f64, &str>>,
diff --git a/impit-python/src/request.rs b/impit-python/src/request.rs
index 07a26da6..4e9102dc 100644
--- a/impit-python/src/request.rs
+++ b/impit-python/src/request.rs
@@ -1,7 +1,15 @@
-use std::{collections::HashMap, time::Duration};
+use std::{collections::HashMap, io, time::Duration};
 
+use bytes::Bytes;
 use either::{Either, Left, Right};
-use pyo3::{Bound, PyAny};
+use futures::{stream, Stream};
+use impit::request::ImpitBody;
+use pyo3::{
+    exceptions::{PyStopAsyncIteration, PyStopIteration, PyTypeError},
+    types::PyAnyMethods,
+    Borrowed, Bound, Py, PyAny, PyErr, PyResult, PyTypeInfo, Python,
+};
+use pyo3_async_runtimes::TaskLocals;
 
 /// The sentinel string used as the Python default value for per-request `timeout` parameters.
 ///
@@ -36,13 +44,109 @@ pub(crate) fn parse_timeout(
 use pyo3::FromPyObject;
 
 #[derive(FromPyObject)]
-pub(crate) enum RequestBody<'py> {
+pub(crate) enum RequestBody {
     #[pyo3(transparent, annotation = "bytes")]
     Bytes(Vec<u8>),
     #[pyo3(transparent, annotation = "dict[str, str]")]
     Form(HashMap<String, String>),
+    #[pyo3(transparent, annotation = "Iterable[bytes] | AsyncIterable[bytes]")]
+    Iterator(PyIterator),
     #[pyo3(transparent)]
-    CatchAll(Bound<'py, PyAny>), // This extraction never fails
+    CatchAll(Py<PyAny>), // This extraction never fails
+}
+
+/// A Python iterator over the chunks of a request body.
+pub(crate) enum PyIterator {
+    Sync(Py<PyAny>),
+    Async(Py<PyAny>, TaskLocals),
+}
+
+impl<'py> FromPyObject<'_, 'py> for PyIterator {
+    type Error = PyErr;
+
+    fn extract(object: Borrowed<'_, 'py, PyAny>) -> PyResult<Self> {
+        match object.call_method0("__aiter__") {
+            Ok(iterator) => Ok(Self::Async(
+                iterator.unbind(),
+                TaskLocals::with_running_loop(object.py())?.copy_context(object.py())?,
+            )),
+            Err(_) => Ok(Self::Sync(object.try_iter()?.into_any().unbind())),
+        }
+    }
+}
+
+fn to_chunk<Stop: PyTypeInfo>(next: PyResult<Py<PyAny>>) -> Option<io::Result<Bytes>> {
+    Python::attach(|py| match next {
+        Ok(chunk) => Some(
+            chunk
+                .extract::<Vec<u8>>(py)
+                .map(Bytes::from)
+                .map_err(io::Error::other),
+        ),
+        Err(err) if err.is_instance_of::<Stop>(py) => None,
+        Err(err) => Some(Err(io::Error::other(err))),
+    })
+}
+
+fn to_stream(iterator: PyIterator) -> impl Stream<Item = io::Result<Bytes>> {
+    stream::unfold(iterator, |iterator| async move {
+        let chunk = match &iterator {
+            PyIterator::Sync(iterator) => {
+                let iterator = Python::attach(|py| iterator.clone_ref(py));
+                tokio::task::spawn_blocking(move || {
+                    to_chunk::<PyStopIteration>(Python::attach(|py| {
+                        iterator
+                            .bind(py)
+                            .call_method0("__next__")
+                            .map(Bound::unbind)
+                    }))
+                })
+                .await
+                .unwrap_or_else(|err| Some(Err(io::Error::other(err))))
+            }
+            PyIterator::Async(iterator, locals) => {
+                let next = Python::attach(|py| {
+                    pyo3_async_runtimes::into_future_with_locals(
+                        locals,
+                        iterator.bind(py).call_method0("__anext__")?,
+                    )
+                });
+                to_chunk::<PyStopAsyncIteration>(match next {
+                    Ok(next) => next.await,
+                    Err(err) => Err(err),
+                })
+            }
+        };
+
+        Some((chunk?, iterator))
+    })
+}
+
+/// Converts the Python request body into an [`ImpitBody`], streaming it if it is an iterator.
+pub(crate) fn to_body(
+    data: Option<RequestBody>,
+    headers: &mut Option<HashMap<String, String>>,
+) -> PyResult<ImpitBody> {
+    Ok(match data {
+        None => ImpitBody::Empty,
+        Some(RequestBody::Bytes(bytes)) => bytes.into(),
+        Some(RequestBody::Form(form)) => {
+            headers.get_or_insert_default().insert(
+                "Content-Type".to_string(),
+                "application/x-www-form-urlencoded".to_string(),
+            );
+            form_to_bytes(form).into()
+        }
+        Some(RequestBody::Iterator(iterator)) => ImpitBody::from_stream(to_stream(iterator)),
+        Some(RequestBody::CatchAll(object)) => {
+            return Err(Python::attach(|py| {
+                PyErr::new::<PyTypeError, _>(format!(
+                    "Unsupported data type in request body: {}",
+                    object.bind(py).get_type()
+                ))
+            }))
+        }
+    })
 }
 
 pub fn form_to_bytes(data: HashMap<String, String>) -> Vec<u8> {
diff --git a/impit-python/test/async_client_test.py b/impit-python/test/async_client_test.py
index b062e305..7bcf6ea3 100644
--- a/impit-python/test/async_client_test.py
+++ b/impit-python/test/async_client_test.py
@@ -2,6 +2,7 @@
 import json
 import socket
 import threading
+from collections.abc import AsyncIterator
 from http.cookiejar import Cookie, CookieJar
 from typing import Literal
 
@@ -526,6 +527,19 @@ async def test_passing_string_body(self, browser: Browser) -> None:
         assert response.status_code == 200
         assert json.loads(response.text)['data'] == '{"Impit-Test":"foořžš"}'
 
+    @pytest.mark.asyncio
+    async def test_passing_async_iterator_body(self, browser: Browser) -> None:
+        impit = AsyncClient(browser=browser)
+
+        async def chunks() -> AsyncIterator[bytes]:
+            yield b'{"Impit-Test":'
+            yield b'"foo"}'
+
+        response = await impit.post(get_httpbin_url('/post'), content=chunks())
+        assert response.status_code == 200
+        assert json.loads(response.text)['data'] == '{"Impit-Test":"foo"}'
+        assert json.loads(response.text)['headers']['Transfer-Encoding'] == 'chunked'
+
     @pytest.mark.asyncio
     async def test_passing_string_body_in_data(self, browser: Browser) -> None:
         impit = AsyncClient(browser=browser)
diff --git a/impit-python/test/basic_client_test.py b/impit-python/test/basic_client_test.py
index f78bffe6..f1e1f80a 100644
--- a/impit-python/test/basic_client_test.py
+++ b/impit-python/test/basic_client_test.py
@@ -2,6 +2,7 @@
 import socket
 import threading
 import time
+from collections.abc import Iterator
 from http.cookiejar import Cookie, CookieJar
 from typing import Literal
 
@@ -454,6 +455,18 @@ def test_passing_string_body(self, browser: Browser) -> None:
         assert response.status_code == 200
         assert response.json()['data'] == '{"Impit-Test":"foořžš"}'
 
+    def test_passing_iterator_body(self, browser: Browser) -> None:
+        impit = Client(browser=browser)
+
+        def chunks() -> Iterator[bytes]:
+            yield b'{"Impit-Test":'
+            yield b'"foo"}'
+
+        response = impit.post(get_httpbin_url('/post'), content=chunks())
+        assert response.status_code == 200
+        assert response.json()['data'] == '{"Impit-Test":"foo"}'
+        assert response.json()['headers']['Transfer-Encoding'] == 'chunked'
+
     def test_passing_string_body_in_data(self, browser: Browser) -> None:
         impit = Client(browser=browser)