diff --git a/src/calibre/ai/open_router/backend.py b/src/calibre/ai/open_router/backend.py
index 0d85d204e5..be91d3ae65 100644
--- a/src/calibre/ai/open_router/backend.py
+++ b/src/calibre/ai/open_router/backend.py
@@ -1,5 +1,135 @@
 #!/usr/bin/env python
 # License: GPLv3 Copyright: 2025, Kovid Goyal <kovid at kovidgoyal.net>
 
+import datetime
+import json
+import os
+import tempfile
+from contextlib import closing, suppress
+from functools import lru_cache
+from threading import Thread
+from typing import NamedTuple
+
+from calibre import browser
+from calibre.constants import __version__, cache_dir
+from calibre.utils.lock import SingleInstance
 
 module_version = 1  # needed for live updates
+
+
+def get_browser():
+    ans = browser(user_agent=f'calibre {__version__}')
+    return ans
+
+
+def singleinstance():
+    return SingleInstance('calibre-open-router')
+
+
+def atomic_write(path, data):
+    mode = 'w' if isinstance(data, str) else 'wb'
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    with tempfile.NamedTemporaryFile(mode, delete=False, dir=os.path.dirname(path)) as f:
+        f.write(data)
+    with singleinstance():
+        os.replace(f.name, path)
+
+
+def atomic_read(path):
+    with singleinstance(), open(path, 'rb') as f:
+        return f.read()
+
+
+def download_models_list():
+    url = 'https://openrouter.ai/api/v1/models'
+    br = get_browser()
+    with closing(br.open(url)) as src:
+        return src.read()
+
+
+def update_cached_models_data(cache_loc):
+    raw = download_models_list()
+    atomic_write(cache_loc, raw)
+
+
+def schedule_update_of_cached_models_data(cache_loc):
+    mtime = 0
+    with suppress(OSError):
+        mtime = os.path.getmtime(cache_loc)
+    modtime = datetime.datetime.fromtimestamp(mtime)
+    current_time = datetime.datetime.now()
+    if current_time - modtime < datetime.timedelta(days=1):
+        return
+
+    Thread(daemon=True, target=update_cached_models_data, args=(cache_loc,)).start()
+
+
+@lru_cache(2)
+def get_available_models():
+    cache_loc = os.path.join(cache_dir(), 'openrouter', 'models-v1.json')
+    with suppress(OSError):
+        data = json.loads(atomic_read(cache_loc))
+        schedule_update_of_cached_models_data(cache_loc)
+        return parse_models_list(data)
+    raw = download_models_list()
+    atomic_write(cache_loc, raw)
+    return parse_models_list(json.loads(raw))
+
+
+class Pricing(NamedTuple):
+    # Values are in USD per token/request/unit
+    input_token: float  # cost per input token
+    output_token: float  # cost per output token
+    request: float  # per API request
+    image: float  # per image
+    web_search: float  # per web search
+    internal_reasoning: float  # cost per internal reasoning token
+    input_cache_read: float  # cost per cached input token read
+    input_cache_write: float  # cost per cached input token write
+
+    @classmethod
+    def from_dict(cls, x: dict[str, str]) -> 'Pricing':
+        return Pricing(
+            input_token=float(x['prompt']), output_token=float(x['completion']), request=float(x.get('request', 0)),
+            image=float(x.get('image', 0)), web_search=float(x.get('web_search', 0)),
+            internal_reasoning=float(x.get('internal_reasoning', 0)),
+            input_cache_read=float(x.get('input_cache_read', 0)), input_cache_write=float(x.get('input_cache_write', 0)),
+        )
+
+
+class Model(NamedTuple):
+    name: str
+    id: str
+    created: int
+    description: str
+    context_length: int
+    pricing: Pricing
+    parameters: tuple[str, ...]
+    is_moderated: bool
+    supports_text_to_text: bool
+    tokenizer: str
+
+    @classmethod
+    def from_dict(cls, x: dict[str, object]) -> 'Model':
+        arch = x['architecture']
+        return Model(
+            name=x['name'], id=x['id'], created=datetime.datetime.fromtimestamp(x['created'], datetime.timezone.utc),
+            description=x['description'], context_length=x['context_length'],
+            parameters=tuple(x['supported_parameters']), pricing=Pricing.from_dict(x['pricing']),
+            is_moderated=x['top_provider']['is_moderated'], tokenizer=arch['tokenizer'],
+            supports_text_to_text='text' in arch['input_modalities'] and 'text' in arch['output_modalities'],
+        )
+
+
+def parse_models_list(entries) -> dict[str, Model]:
+    ans = {}
+    for entry in entries['data']:
+        e = Model.from_dict(entry)
+        ans[e.id] = e
+    return ans
+
+
+if __name__ == '__main__':
+    from pprint import pprint
+    for m in get_available_models().values():
+        pprint(m)