diff --git a/changelog.md b/changelog.md
index 15adcab..3f263a0 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,16 @@
 # Changelog
 
+## 2025-08-19 - 4.3.1 - fix(core)
+Improve streaming support and timeout handling; add browser streaming & timeout tests and README clarifications
+
+- core_fetch: accept Uint8Array and Buffer-like bodies; set fetch duplex for ReadableStream bodies so streaming requests work in environments that require duplex
+- core_fetch: implement AbortController-based timeouts and ensure timeouts are cleared on success/error to avoid hanging timers
+- core_node: add explicit request timeout handling (request.setTimeout) and hard-data-cutting timeout tracking with proper timeoutId clear on success/error
+- client: document that raw(streamFunc) is Node-only (not supported in browsers)
+- tests: add browser streaming tests (test/test.streaming.browser.ts) that exercise buffer() and web ReadableStream via stream()
+- tests: add timeout tests (test/test.timeout.ts) to validate clearing timers, enforcing timeouts, and preventing timer leaks across multiple requests
+- docs: update README streaming section to clarify cross-platform behavior of buffer(), stream(), and raw() methods
+
 ## 2025-08-18 - 4.3.0 - feat(client/smartrequest)
 Add streaming and raw buffer support to SmartRequest (buffer, stream, raw); update docs and tests
 
diff --git a/readme.md b/readme.md
index 6815172..e7ecd4c 100644
--- a/readme.md
+++ b/readme.md
@@ -379,15 +379,20 @@ async function uploadBinaryData() {
 #### Streaming Methods
 
 - **`.buffer(data, contentType?)`** - Stream a Buffer or Uint8Array directly
-  - `data`: Buffer or Uint8Array to send
+  - `data`: Buffer (Node.js) or Uint8Array (both platforms) to send
   - `contentType`: Optional content type (defaults to 'application/octet-stream')
+  - ✅ Works in both Node.js and browsers
 
-- **`.stream(stream, contentType?)`** - Stream from Node.js ReadableStream or web ReadableStream
-  - `stream`: The stream to pipe to the request
+- **`.stream(stream, contentType?)`** - Stream from ReadableStream
+  - `stream`: Web ReadableStream (both platforms) or Node.js stream (Node.js only)
   - `contentType`: Optional content type
+  - ✅ Web ReadableStream works in both Node.js and browsers
+  - ⚠️ Node.js streams only work in Node.js environment
 
-- **`.raw(streamFunc)`** - Advanced control over request streaming (Node.js only)
+- **`.raw(streamFunc)`** - Advanced control over request streaming
   - `streamFunc`: Function that receives the raw request object for custom streaming
+  - ❌ **Node.js only** - not supported in browsers
+  - Use for advanced scenarios like chunked transfer encoding
 
 These methods are particularly useful for:
 - Uploading large files without loading them into memory
diff --git a/test/test.streaming.browser.ts b/test/test.streaming.browser.ts
new file mode 100644
index 0000000..f92e84e
--- /dev/null
+++ b/test/test.streaming.browser.ts
@@ -0,0 +1,41 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { SmartRequest } from '../ts/index.js';
+
+tap.test('browser: should send Uint8Array using buffer() method', async () => {
+  const testData = new Uint8Array([72, 101, 108, 108, 111]); // "Hello" in ASCII
+  
+  const smartRequest = SmartRequest.create()
+    .url('https://httpbin.org/post')
+    .buffer(testData, 'application/octet-stream')
+    .method('POST');
+  
+  const response = await smartRequest.post();
+  const data = await response.json();
+  
+  expect(data).toHaveProperty('data');
+  expect(data.headers['Content-Type']).toEqual('application/octet-stream');
+});
+
+tap.test('browser: should send web ReadableStream using stream() method', async () => {
+  // Create a web ReadableStream
+  const encoder = new TextEncoder();
+  const stream = new ReadableStream({
+    start(controller) {
+      controller.enqueue(encoder.encode('Test stream data'));
+      controller.close();
+    }
+  });
+  
+  const smartRequest = SmartRequest.create()
+    .url('https://httpbin.org/post')
+    .stream(stream, 'text/plain')
+    .method('POST');
+  
+  const response = await smartRequest.post();
+  const data = await response.json();
+  
+  expect(data).toHaveProperty('data');
+  // httpbin should receive the streamed data
+});
+
+export default tap.start();
\ No newline at end of file
diff --git a/test/test.timeout.ts b/test/test.timeout.ts
new file mode 100644
index 0000000..e492c99
--- /dev/null
+++ b/test/test.timeout.ts
@@ -0,0 +1,60 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { SmartRequest } from '../ts/index.js';
+
+tap.test('should clear timeout when request completes before timeout', async () => {
+  // Set a long timeout that would keep the process alive if not cleared
+  const response = await SmartRequest.create()
+    .url('https://httpbin.org/delay/1') // 1 second delay
+    .timeout(10000) // 10 second timeout (much longer than needed)
+    .get();
+  
+  const data = await response.json();
+  expect(data).toBeDefined();
+  
+  // The test should complete quickly, not wait for the 10 second timeout
+  // If the timeout isn't cleared, the process would hang for 10 seconds
+});
+
+tap.test('should timeout when request takes longer than timeout', async () => {
+  let errorThrown = false;
+  
+  try {
+    // Try to fetch with a very short timeout
+    await SmartRequest.create()
+      .url('https://httpbin.org/delay/3') // 3 second delay
+      .timeout(100) // 100ms timeout (will fail)
+      .get();
+  } catch (error) {
+    errorThrown = true;
+    expect(error.message).toContain('Request timed out');
+  }
+  
+  expect(errorThrown).toBeTrue();
+});
+
+tap.test('should not leak timers with multiple successful requests', async () => {
+  // Make multiple requests with timeouts to ensure no timer leaks
+  const promises = [];
+  
+  for (let i = 0; i < 5; i++) {
+    promises.push(
+      SmartRequest.create()
+        .url('https://httpbin.org/get')
+        .timeout(5000) // 5 second timeout
+        .get()
+        .then(response => response.json())
+    );
+  }
+  
+  const results = await Promise.all(promises);
+  
+  // All requests should complete successfully
+  expect(results).toHaveLength(5);
+  results.forEach(result => {
+    expect(result).toBeDefined();
+  });
+  
+  // Process should exit cleanly after this test without hanging
+});
+
+export default tap.start();
\ No newline at end of file
diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index d89a553..f111254 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartrequest',
-  version: '4.3.0',
+  version: '4.3.1',
   description: 'A module for modern HTTP/HTTPS requests with support for form data, file uploads, JSON, binary data, streams, and more.'
 }
diff --git a/ts/client/smartrequest.ts b/ts/client/smartrequest.ts
index 64ce276..0c430d2 100644
--- a/ts/client/smartrequest.ts
+++ b/ts/client/smartrequest.ts
@@ -164,7 +164,7 @@ export class SmartRequest<T = any> {
   /**
    * Provide a custom function to handle raw request streaming
    * This gives full control over the request body streaming
-   * Note: Only works in Node.js environment
+   * Note: Only works in Node.js environment, not supported in browsers
    */
   raw(streamFunc: RawStreamFunction): this {
     // Store the raw streaming function to be used later
diff --git a/ts/core_fetch/request.ts b/ts/core_fetch/request.ts
index 932ca5d..c9606ef 100644
--- a/ts/core_fetch/request.ts
+++ b/ts/core_fetch/request.ts
@@ -9,6 +9,9 @@ export class CoreRequest extends AbstractCoreRequest<
   types.ICoreRequestOptions,
   CoreResponse
 > {
+  private timeoutId: ReturnType<typeof setTimeout> | null = null;
+  private abortController: AbortController | null = null;
+
   constructor(url: string, options: types.ICoreRequestOptions = {}) {
     super(url, options);
 
@@ -61,11 +64,19 @@ export class CoreRequest extends AbstractCoreRequest<
       if (
         typeof this.options.requestBody === 'string' ||
         this.options.requestBody instanceof ArrayBuffer ||
+        this.options.requestBody instanceof Uint8Array ||
         this.options.requestBody instanceof FormData ||
         this.options.requestBody instanceof URLSearchParams ||
-        this.options.requestBody instanceof ReadableStream
+        this.options.requestBody instanceof ReadableStream ||
+        // Check for Buffer (Node.js polyfills in browser may provide this)
+        (typeof Buffer !== 'undefined' && this.options.requestBody instanceof Buffer)
       ) {
         fetchOptions.body = this.options.requestBody;
+        
+        // If streaming, we need to set duplex mode
+        if (this.options.requestBody instanceof ReadableStream) {
+          (fetchOptions as any).duplex = 'half';
+        }
       } else {
         // Convert objects to JSON
         fetchOptions.body = JSON.stringify(this.options.requestBody);
@@ -92,9 +103,13 @@ export class CoreRequest extends AbstractCoreRequest<
     if (this.options.timeout || this.options.hardDataCuttingTimeout) {
       const timeout =
         this.options.hardDataCuttingTimeout || this.options.timeout;
-      const controller = new AbortController();
-      setTimeout(() => controller.abort(), timeout);
-      fetchOptions.signal = controller.signal;
+      this.abortController = new AbortController();
+      this.timeoutId = setTimeout(() => {
+        if (this.abortController) {
+          this.abortController.abort();
+        }
+      }, timeout);
+      fetchOptions.signal = this.abortController.signal;
     }
 
     return fetchOptions;
@@ -117,8 +132,12 @@ export class CoreRequest extends AbstractCoreRequest<
 
     try {
       const response = await fetch(url, options);
+      // Clear timeout on successful response
+      this.clearTimeout();
       return response;
     } catch (error) {
+      // Clear timeout on error
+      this.clearTimeout();
       if (error.name === 'AbortError') {
         throw new Error('Request timed out');
       }
@@ -126,6 +145,19 @@ export class CoreRequest extends AbstractCoreRequest<
     }
   }
 
+  /**
+   * Clear the timeout and abort controller
+   */
+  private clearTimeout(): void {
+    if (this.timeoutId) {
+      clearTimeout(this.timeoutId);
+      this.timeoutId = null;
+    }
+    if (this.abortController) {
+      this.abortController = null;
+    }
+  }
+
   /**
    * Static factory method to create and fire a request
    */
diff --git a/ts/core_node/request.ts b/ts/core_node/request.ts
index 593a51c..2d1f45a 100644
--- a/ts/core_node/request.ts
+++ b/ts/core_node/request.ts
@@ -119,10 +119,11 @@ export class CoreRequest extends AbstractCoreRequest<
     }
 
     // Perform the request
+    let timeoutId: NodeJS.Timeout | null = null;
     const request = requestModule.request(this.options, async (response) => {
       // Handle hard timeout
       if (this.options.hardDataCuttingTimeout) {
-        setTimeout(() => {
+        timeoutId = setTimeout(() => {
           response.destroy();
           done.reject(new Error('Request timed out'));
         }, this.options.hardDataCuttingTimeout);
@@ -132,6 +133,14 @@ export class CoreRequest extends AbstractCoreRequest<
       done.resolve(response);
     });
 
+    // Set request timeout (Node.js built-in timeout)
+    if (this.options.timeout) {
+      request.setTimeout(this.options.timeout, () => {
+        request.destroy();
+        done.reject(new Error('Request timed out'));
+      });
+    }
+
     // Write request body
     if (this.options.requestBody) {
       if (this.options.requestBody instanceof plugins.formData) {
@@ -159,11 +168,23 @@ export class CoreRequest extends AbstractCoreRequest<
     request.on('error', (e) => {
       console.error(e);
       request.destroy();
+      // Clear timeout on error
+      if (timeoutId) {
+        clearTimeout(timeoutId);
+        timeoutId = null;
+      }
       done.reject(e);
     });
 
     // Get response and handle response errors
     const response = await done.promise;
+    
+    // Clear timeout on successful response
+    if (timeoutId) {
+      clearTimeout(timeoutId);
+      timeoutId = null;
+    }
+    
     response.on('error', (err) => {
       console.error(err);
       response.destroy();