diff --git a/src/calibre/scraper/qt.py b/src/calibre/scraper/qt.py
new file mode 100644
index 0000000000..37ab85ad8a
--- /dev/null
+++ b/src/calibre/scraper/qt.py
@@ -0,0 +1,216 @@
+#!/usr/bin/env python
+# License: GPLv3 Copyright: 2024, Kovid Goyal <kovid at kovidgoyal.net>
+
+import json
+import os
+import shutil
+import time
+from contextlib import suppress
+from io import BytesIO
+from queue import Queue
+from threading import RLock, Thread
+from urllib.error import URLError
+from urllib.parse import urlencode
+from urllib.request import Request
+
+from calibre.ptempfile import PersistentTemporaryDirectory
+
+
+class FakeResponse:
+
+    def __init__(self):
+        self.queue = Queue()
+        self.done = False
+        self.final_url = ''
+        self.data = BytesIO()
+
+    def _wait(self):
+        if self.done:
+            return
+        self.done = True
+        res = self.queue.get()
+        if res['action'] == 'input_error':
+            raise Exception(res['error'])
+        self.final_url = res['final_url']
+        if 'error' in res:
+            ex = URLError(res['error'])
+            ex.worth_retry = bool(res.get('worth_retry'))
+            raise ex
+        self.data = open(res['output'], 'rb')
+
+    def read(self, *a, **kw):
+        self._wait()
+        ans = self.data.read(*a, **kw)
+        return ans
+
+    def seek(self, *a, **kw):
+        self._wait()
+        return self.data.seek(*a, **kw)
+
+    def tell(self, *a, **kw):
+        return self.data.tell(*a, **kw)
+
+    def geturl(self):
+        self._wait()
+        return self.final_url
+
+    def close(self):
+        self.data.close()
+
+
+class Browser:
+
+    def __init__(self, user_agent: str = '', headers: tuple[tuple[str, str], ...] = (), start_worker: bool = False):
+        self.tdir = ''
+        self.worker = self.dispatcher = None
+        self.dispatch_map = {}
+        self.id_counter = 0
+        self.addheaders: list[tuple[str, str]] = list(headers)
+        self.user_agent = user_agent
+        self.lock = RLock()
+        self.shutting_down = False
+        if start_worker:
+            self._ensure_state()
+
+    def open(self, url_or_request: Request, data=None, timeout=None):
+        method = 'POST' if data else 'GET'
+        headers = []
+        if hasattr(url_or_request, 'get_method'):
+            r = url_or_request
+            method = r.get_method()
+            data = data or r.data
+            headers = r.header_items()
+            url = r.full_url
+        else:
+            url = url_or_request
+
+        def has_header(x: str) -> bool:
+            x = x.lower()
+            for (h, v) in headers:
+                if h.lower() == x:
+                    return True
+            return False
+
+        if isinstance(data, dict):
+            headers.append(('Content-Type', 'application/x-www-form-urlencoded'))
+            data = urlencode(data)
+        if isinstance(data, str):
+            data = data.encode('utf-8')
+            if not has_header('Content-Type'):
+                headers.append(('Content-Type', 'text/plain'))
+
+        with self.lock:
+            self._ensure_state()
+            self.id_counter += 1
+            cmd = {
+                'action': 'download', 'id': self.id_counter, 'url': url, 'method': method, 'timeout': timeout,
+                'headers': self.addheaders + headers}
+            if data:
+                with open(os.path.join(self.tdir, f'i{self.id_counter}'), 'wb') as f:
+                    if hasattr(data, 'read'):
+                        shutil.copyfileobj(data, f)
+                    else:
+                        f.write(data)
+                cmd['data_path'] = f.name
+            res = FakeResponse()
+            self.dispatch_map[self.id_counter] = res.queue
+            self._send_command(cmd)
+        return res
+
+    open_novisit = open
+
+    def set_simple_cookie(self, name: str, value: str, domain: str | None = None, path: str | None = '/'):
+        '''
+        Set a simple cookie using a name and value. If domain is specified, the cookie is only sent with requests
+        to matching domains, otherwise it is sent with all requests. The leading dot in domain is optional.
+        Similarly, by default all paths match, to restrict to certain path use the path parameter.
+        '''
+        c = {'name': name, 'value': value, 'domain': domain, 'path': path}
+        self._send_command({'action': 'set_cookies', 'cookies':[c]})
+
+    def set_user_agent(self, val: str = '') -> None:
+        self.user_agent = val
+        self._send_command({'action': 'set_user_agent', 'user_agent': val})
+
+    def clone_browser(self):
+        return self
+
+    def _send_command(self, cmd):
+        with self.lock:
+            self.worker.stdin.write(json.dumps(cmd).encode())
+            self.worker.stdin.write(b'\n')
+            self.worker.stdin.flush()
+
+    def _ensure_state(self):
+        with self.lock:
+            if not self.tdir:
+                self.tdir = PersistentTemporaryDirectory()
+                self.worker = run_worker(self.tdir, self.user_agent)
+                self.dispatcher = Thread(target=self._dispatch, daemon=True)
+                self.dispatcher.start()
+
+    def _dispatch(self):
+        try:
+            for line in self.worker.stdout:
+                cmd = json.loads(line)
+                if cmd.get('action') == 'finished':
+                    with self.lock:
+                        q = self.dispatch_map.pop(cmd['id'])
+                    q.put(cmd)
+                else:
+                    raise Exception(f'Unexpected response from backend fetch worker process: {cmd}')
+        except Exception:
+            if not self.shutting_down:
+                import traceback
+                traceback.print_exc()
+
+    def shutdown(self):
+        self.shutting_down = True
+        import shutil
+        if self.worker:
+            with suppress(OSError):
+                self.worker.stdin.close()
+            with suppress(OSError):
+                self.worker.stdout.close()
+            give_up_at = time.monotonic() + 1.5
+            while time.monotonic() < give_up_at and self.worker.poll() is None:
+                time.sleep(0.01)
+            if self.worker.poll() is None:
+                self.worker.kill()
+        if self.tdir:
+            with suppress(OSError):
+                shutil.rmtree(self.tdir)
+            self.tdir = ''
+        if self.dispatcher:
+            self.dispatcher.join()
+            self.dispatcher = None
+
+    def __del__(self):
+        self.shutdown()
+
+
+def run_worker(tdir: str, user_agent: str):
+    from calibre.utils.ipc.simple_worker import start_pipe_worker
+    return start_pipe_worker(f'from calibre.scraper.qt import worker; worker({tdir!r}, {user_agent!r})')
+
+
+def worker(*args):
+    from calibre.gui2 import must_use_qt
+    must_use_qt()
+    from .qt_backend import worker
+    worker(*args)
+
+
+def develop():
+    import sys
+    br = Browser()
+    try:
+        for url in sys.argv[1:]:
+            res = br.open(url)
+            print(url, len(res.read()))
+    finally:
+        del br
+
+
+if __name__ == '__main__':
+    develop()
diff --git a/src/calibre/scraper/qt_backend.py b/src/calibre/scraper/qt_backend.py
index a4d51d852f..f4ef73d221 100644
--- a/src/calibre/scraper/qt_backend.py
+++ b/src/calibre/scraper/qt_backend.py
@@ -95,7 +95,8 @@ class DownloadRequest(QObject):
 
     def on_data_available(self) -> None:
         with open(self.output_path, 'ab') as f:
-            f.write(memoryview(self.reply.readAll()))
+            ba = self.reply.readAll()
+            f.write(memoryview(ba))
 
     def on_ssl_errors(self, err) -> None:
         pass
@@ -106,6 +107,16 @@ class DownloadRequest(QObject):
                   'final_url': qurl_to_string(self.reply.url())}
 
         if e != QNetworkReply.NetworkError.NoError:
+            if e in (
+                QNetworkReply.NetworkError.TimeoutError,
+                QNetworkReply.NetworkError.TemporaryNetworkFailureError,
+
+                QNetworkReply.NetworkError.ConnectionRefusedError,
+                QNetworkReply.NetworkError.RemoteHostClosedError,
+                QNetworkReply.NetworkError.OperationCanceledError,  # abort() called in overall timeout check
+                QNetworkReply.NetworkError.SslHandshakeFailedError,
+            ):
+                self.worth_retry = True
             es = f'{e}: {self.reply.errorString()}'
             result['error'], result['worth_retry'] = es, self.worth_retry
         return result
@@ -248,27 +259,25 @@ def request_from_cmd(cmd: dict[str, Any], filename: str) -> Request:
     if timeout is None:
         timeout = default_timeout
     req: Request = {
-        'id': cmd.get(id) or 0,
+        'id': int(cmd['id']),
         'url': cmd['url'],
         'headers': cmd.get('headers') or [],
         'data_path': cmd.get('data_path') or '',
         'method': cmd.get('method') or 'get',
         'filename': filename,
-        'timeout': timeout,
+        'timeout': float(timeout),
     }
     return req
 
 
 def read_commands(backend: FetchBackend, tdir: str) -> None:
-    file_counter = 0
     error_msg = ''
     try:
         for line in sys.stdin:
             cmd = json.loads(line)
             ac = cmd['action']
             if ac == 'download':
-                file_counter += 1
-                backend.request_download.emit(request_from_cmd(cmd, str(file_counter)))
+                backend.request_download.emit(request_from_cmd(cmd, f'o{cmd["id"]}'))
             elif ac == 'set_cookies':
                 backend.set_cookies.emit(cmd['cookies'])
             elif ac == 'set_user_agent':
@@ -285,7 +294,7 @@ def read_commands(backend: FetchBackend, tdir: str) -> None:
 def worker(tdir: str, user_agent: str) -> None:
     app = QApplication.instance()
     sys.stdout = sys.stderr
-    backend = FetchBackend(parent=app, user_agent=user_agent)
+    backend = FetchBackend(parent=app, user_agent=user_agent, output_dir=tdir)
     try:
         read_thread = Thread(target=read_commands, args=(backend, tdir), daemon=True)
         read_thread.start()
@@ -312,7 +321,7 @@ def develop(url: str) -> None:
 
     backend.download_finished.connect(download_finished)
     for i, url in enumerate(sys.argv[1:]):
-        backend.download(request_from_cmd({'url':url}, f'test-output-{i}'))
+        backend.download(request_from_cmd({'url':url, 'id': i}, f'test-output-{i}'))
         num_left += 1
     app.exec()
 
diff --git a/src/calibre/scraper/test_fetch_backend.py b/src/calibre/scraper/test_fetch_backend.py
index 7e00037989..d0933a6559 100644
--- a/src/calibre/scraper/test_fetch_backend.py
+++ b/src/calibre/scraper/test_fetch_backend.py
@@ -12,8 +12,8 @@ from lxml.html import fromstring, tostring
 
 from calibre.utils.resources import get_path as P
 
+from .qt import Browser
 from .simple import Overseer
-from .webengine_download import Browser
 
 skip = ''
 is_sanitized = 'libasan' in os.environ.get('LD_PRELOAD', '')
@@ -158,7 +158,7 @@ class TestFetchBackend(unittest.TestCase):
             br.set_user_agent('man in black')
             r = get()
             self.ae(r['headers']['User-Agent'], ['man in black'])
-            self.ae(r['headers']['Cookie'], ['sc=1; cook=ie'])
+            self.ae(r['headers']['Cookie'], ['cook=ie; sc=1'])
         finally:
             br.shutdown()