diff --git a/chattool/__init__.py b/chattool/__init__.py
index ea4a91d..9f5efb7 100644
--- a/chattool/__init__.py
+++ b/chattool/__init__.py
@@ -2,7 +2,7 @@
 
 __author__ = """Rex Wang"""
 __email__ = '1073853456@qq.com'
-__version__ = '2.6.2'
+__version__ = '3.0.0'
 
 import os, sys, requests
 from .chattool import Chat, Resp
diff --git a/chattool/asynctool.py b/chattool/asynctool.py
index 8c801f2..c474470 100644
--- a/chattool/asynctool.py
+++ b/chattool/asynctool.py
@@ -83,11 +83,11 @@ async def async_process_msgs( chatlogs:List[List[Dict]]
     sem = asyncio.Semaphore(ncoroutines)
     locker = asyncio.Lock()
 
-    async def chat_complete(ind, locker, chatlog, chkpoint, **options):
-        payload = {"messages": chatlog}
+    async def chat_complete(ind, locker, chat_log, chkpoint, **options):
+        payload = {"messages": chat_log}
         payload.update(options)
         if max_tokens is not None:
-            payload['max_tokens'] = max_tokens(chatlog)
+            payload['max_tokens'] = max_tokens(chat_log)
         data = json.dumps(payload)
         resp = await async_post( session=session
                                , sem=sem
@@ -99,22 +99,22 @@ async def chat_complete(ind, locker, chatlog, chkpoint, **options):
                                , timeout=timeout)
         ## saving files
         if resp is None: return 0, 0
-        chatlog.append(resp.message)
-        chat = Chat(chatlog)
+        chat_log.append(resp.message)
+        chat = Chat(chat_log)
         async with locker: # locker | not necessary for normal IO
-            chat.savewithid(chkpoint, chatid=ind)
+            chat.save(chkpoint, index=ind)
         return ind, resp.cost()
 
     async with sem, aiohttp.ClientSession() as session:
         tasks = []
-        for ind, chatlog in enumerate(chatlogs):
+        for ind, chat_log in enumerate(chatlogs):
             if chats[ind] is not None: # skip completed chats
                 continue
             tasks.append(
                 asyncio.create_task(
                     chat_complete( ind=ind
                                  , locker=locker
-                                 , chatlog=chatlog
+                                 , chat_log=chat_log
                                  , chkpoint=chkpoint
                                  , **options)))
         try: # for mac or linux
@@ -186,7 +186,7 @@ def async_chat_completion( msgs:Union[List[List[Dict]], str]
     # run async process
     assert ncoroutines > 0, "ncoroutines must be greater than 0!"
     if isinstance(max_tokens, int):
-         max_tokens = lambda chatlog: max_tokens
+         max_tokens = lambda chat_log: max_tokens
     args = {
         "chatlogs": chatlogs,
         "chkpoint": chkpoint,
diff --git a/chattool/chattool.py b/chattool/chattool.py
index da14c88..faeef3f 100644
--- a/chattool/chattool.py
+++ b/chattool/chattool.py
@@ -102,7 +102,7 @@ def deepcopy(self):
                    , name2func=self.name2func
                    , base_url=self.base_url)
 
-    def save(self, path:str, mode:str='a'):
+    def save(self, path:str, mode:str='a', index:int=0):
         """
         Save the chat log to a file. Each line is a json string.
 
@@ -115,24 +115,7 @@ def save(self, path:str, mode:str='a'):
         pathname = os.path.dirname(path).strip()
         if pathname != '':
             os.makedirs(pathname, exist_ok=True)
-        with open(path, mode, encoding='utf-8') as f:
-            f.write(json.dumps(self.chat_log, ensure_ascii=False) + '\n')
-        return
-    
-    def savewithid(self, path:str, chatid:int, mode:str='a'):
-        """Save the chat log with chat id. Each line is a json string.
-
-        Args:
-            path (str): path to the file
-            chatid (int): chat id
-            mode (str, optional): mode to open the file. Defaults to 'a'.
-        """
-        assert mode in ['a', 'w'], "saving mode should be 'a' or 'w'"
-        # make path if not exists
-        pathname = os.path.dirname(path).strip()
-        if pathname != '':
-            os.makedirs(pathname, exist_ok=True)
-        data = {"chatid": chatid, "chatlog": self.chat_log}
+        data = {"index": index, "chat_log": self.chat_log}
         with open(path, mode, encoding='utf-8') as f:
             f.write(json.dumps(data, ensure_ascii=False) + '\n')
         return
@@ -163,8 +146,8 @@ def load(path:str):
             path (str): path to the file
         """
         with open(path, 'r', encoding='utf-8') as f:
-            chatlog = json.loads(f.read())
-        return Chat(chatlog)
+            chat_log = json.loads(f.read())
+        return Chat(chat_log['chat_log'])
     
     @staticmethod
     def display_role_content(dic:dict, sep:Union[str, None]=None):
diff --git a/chattool/checkpoint.py b/chattool/checkpoint.py
index 7ae80be..0e17eee 100644
--- a/chattool/checkpoint.py
+++ b/chattool/checkpoint.py
@@ -3,13 +3,11 @@
 from .chattool import Chat
 import tqdm
 
-def load_chats( checkpoint:str
-              , withid:bool=False):
+def load_chats( checkpoint:str):
     """Load chats from a checkpoint file
     
     Args:
         checkpoint (str): path to the checkpoint file
-        withid (bool, optional): Deprecated. It is not needed anymore. Defaults to False.
 
     Returns:
         list: chats
@@ -23,25 +21,20 @@ def load_chats( checkpoint:str
         txts = f.read().strip().split('\n')
     ## empty file
     if len(txts) == 1 and txts[0] == '': return []
-
     # get the chatlogs
     logs = [json.loads(txt) for txt in txts]
-    ## chatlogs with chatid
-    if 'chatid' in logs[0]:
-        chat_size, chatlogs = 1, [None]
-        for log in logs:
-            idx = log['chatid']
-            if idx >= chat_size: # extend chatlogs
-                chatlogs.extend([None] * (idx - chat_size + 1))
-                chat_size = idx + 1
-            chatlogs[idx] = log['chatlog']
-        # check if there are missing chatlogs
-        if None in chatlogs:
-            warnings.warn(f"checkpoint file {checkpoint} has unfinished chats")
-    else: ## logs without chatid
-        chatlogs = logs
+    chat_size, chatlogs = 1, [None]
+    for log in logs:
+        idx = log['index']
+        if idx >= chat_size: # extend chatlogs
+            chatlogs.extend([None] * (idx - chat_size + 1))
+            chat_size = idx + 1
+        chatlogs[idx] = log['chat_log']
+    # check if there are missing chatlogs
+    if None in chatlogs:
+        warnings.warn(f"checkpoint file {checkpoint} has unfinished chats")
     # return Chat class
-    return [Chat(chatlog) if chatlog is not None else None for chatlog in chatlogs]
+    return [Chat(chat_log) if chat_log is not None else None for chat_log in chatlogs]
 
 def process_chats( data:List[Any]
                  , data2chat:Callable[[Any], Chat]
@@ -68,13 +61,12 @@ def process_chats( data:List[Any]
     if len(chats) > len(data):
         warnings.warn(f"checkpoint file {checkpoint} has more chats than the data to be processed")
         return chats[:len(data)]
-    
     chats.extend([None] * (len(data) - len(chats)))
     ## process chats
     tq = tqdm.tqdm if not isjupyter else tqdm.notebook.tqdm
     for i in tq(range(len(data))):
         if chats[i] is not None: continue
         chat = data2chat(data[i])
-        chat.save(checkpoint, mode='a')
+        chat.save(checkpoint, mode='a', index=i)
         chats[i] = chat
     return chats
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 3a35c4e..4640092 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
 with open('README.md') as readme_file:
     readme = readme_file.read()
 
-VERSION = '2.6.2'
+VERSION = '3.0.0'
 
 requirements = [
     'Click>=7.0', 'requests>=2.20', "responses>=0.23", 'aiohttp>=3.8',
@@ -35,7 +35,7 @@
     },
     install_requires=requirements,
     license="MIT license",
-    long_description=readme,
+    # long_description=readme,
     long_description_content_type='text/markdown',
     include_package_data=True,
     keywords='chattool',
diff --git a/tests/test_async.py b/tests/test_async.py
index 8001351..b820bb1 100644
--- a/tests/test_async.py
+++ b/tests/test_async.py
@@ -66,8 +66,8 @@ def msg2log(msg):
         chat.system("translate the words from English to Chinese")
         chat.user(msg)
         return chat.chat_log
-    def max_tokens(chatlog):
-        return Chat(chatlog).prompt_token()
+    def max_tokens(chat_log):
+        return Chat(chat_log).prompt_token()
     async_chat_completion(words, chkpoint, clearfile=True, ncoroutines=3, max_tokens=max_tokens, msg2log=msg2log)
 
 def test_normal_process():
diff --git a/tests/test_checkpoint.py b/tests/test_checkpoint.py
index 548cf3c..cd81821 100644
--- a/tests/test_checkpoint.py
+++ b/tests/test_checkpoint.py
@@ -6,11 +6,11 @@ def test_with_checkpoint():
     # save chats without chatid
     chat = Chat()
     checkpath = testpath + "tmp.jsonl"
-    chat.save(checkpath, mode="w")
+    chat.save(checkpath, mode="w", index=0)
     chat = Chat("hello!")
-    chat.save(checkpath) # append
+    chat.save(checkpath, index=1) # append
     chat.assistant("你好, how can I assist you today?")
-    chat.save(checkpath) # append
+    chat.save(checkpath, index=2) # append
     ## load chats
     chats = load_chats(checkpath)
     chat_logs = [
@@ -23,13 +23,13 @@ def test_with_checkpoint():
     # save chats with chatid
     chat = Chat()
     checkpath = testpath + "tmp_withid.jsonl"
-    chat.savewithid(checkpath, mode="w", chatid=0)
+    chat.save(checkpath, mode="w", index=0)
     chat = Chat("hello!")
-    chat.savewithid(checkpath, chatid=3)
+    chat.save(checkpath, index=3)
     chat.assistant("你好, how can I assist you today?")
-    chat.savewithid(checkpath, chatid=2)
+    chat.save(checkpath, index=2)
     ## load chats
-    chats = load_chats(checkpath, withid=True)
+    chats = load_chats(checkpath)
     chat_logs = [
         [],
         None,
diff --git a/tests/testfiles/.keep b/tests/testfiles/.keep
deleted file mode 100644
index e69de29..0000000