diff --git a/assets/docs/dataflow.md b/assets/docs/dataflow.md
index f1e6bb7..29ef4ea 100644
--- a/assets/docs/dataflow.md
+++ b/assets/docs/dataflow.md
@@ -61,7 +61,7 @@ flowchart LR
 
 #### 1.1 Tokenizer (`tokenizer.py`)
 - Implemented based on Byte-Level BPE (BBPE)
-- Supports special tokens: `<bos>`, `<eos>`, `<pad>`, `<|im_start|>`, `<|im_end|>`
+- Supports special tokens: `<｜begin▁of▁sentence｜>`, `<｜end▁of▁sentence｜>`, `<｜▁pad▁｜>`, `<｜im▁start｜>`, `<｜im▁end｜>`
 - Provides `encode`/`decode` methods for mutual conversion between text and token IDs
 - Learns vocabulary from corpus during training, saved as `.json` files
 
diff --git a/astrai/data/tokenizer.py b/astrai/data/tokenizer.py
index ff850e1..1b1ef61 100644
--- a/astrai/data/tokenizer.py
+++ b/astrai/data/tokenizer.py
@@ -1,86 +1,110 @@
-from tokenizers import Tokenizer, Encoding
-from tokenizers import decoders, processors, normalizers, pre_tokenizers
+from abc import ABC, abstractmethod
+from tokenizers import Tokenizer, decoders, processors, normalizers, pre_tokenizers
 from tokenizers.models import BPE
-from tokenizers.trainers import BpeTrainer
+from tokenizers.trainers import BpeTrainer as BpeTrainerImpl
 from typing import List, Union
 
 
-class BpeTokenizer:
-    def __init__(self, path=None):
-        self._control_tokens = ["<bos>", "<eos>", "<pad>"]
-        self._special_tokens = ["<|im_start|>", "<|im_end|>"]
+class BaseTokenizer(ABC):
+    @abstractmethod
+    def _init_tokenizer(self):
+        pass
 
+    @abstractmethod
+    def save(self, path):
+        pass
+
+    @abstractmethod
+    def load(self, path):
+        pass
+
+    @abstractmethod
+    def encode(
+        self,
+        tokens: Union[str, List[str]],
+        out_ids: bool = True,
+        add_special_tokens: bool = False,
+    ) -> List:
+        pass
+
+    @abstractmethod
+    def decode(self, tokens: List[int], skip_special_tokens: bool = True) -> str:
+        pass
+
+    @abstractmethod
+    def __len__(self) -> int:
+        pass
+
+    @property
+    @abstractmethod
+    def stop_ids(self) -> List[int]:
+        pass
+
+    @property
+    @abstractmethod
+    def bos_id(self) -> int:
+        pass
+
+    @property
+    @abstractmethod
+    def eos_id(self) -> int:
+        pass
+
+    @property
+    @abstractmethod
+    def pad_id(self) -> int:
+        pass
+
+
+class BaseTrainer(ABC):
+    def __init__(self, tokenizer: BaseTokenizer):
+        self.tokenizer = tokenizer
+
+    @abstractmethod
+    def train(self, files, vocab_size, min_freq, **kwargs):
+        pass
+
+    @abstractmethod
+    def train_from_iterator(self, iterator, vocab_size, min_freq, **kwargs):
+        pass
+
+
+class BpeTokenizer(BaseTokenizer):
+    def __init__(
+        self,
+        control_tokens: List[str] = None,
+        special_tokens: List[str] = None,
+        path=None,
+    ):
+        self._control_tokens = control_tokens or [
+            "<｜begin▁of▁sentence｜>",
+            "<｜end▁of▁sentence｜>",
+            "<｜▁pad▁｜>",
+        ]
+        self._special_tokens = special_tokens or [
+            "<｜im▁start｜>",
+            "<｜im▁end｜>",
+        ]
+        self._tokenizer = None
+        self._init_tokenizer()
+        if path is not None:
+            self.load(path)
+
+    def _init_tokenizer(self):
         model = BPE()
         self._tokenizer = Tokenizer(model)
         self._tokenizer.normalizer = normalizers.Sequence(
             [normalizers.NFC(), normalizers.Strip()]
         )
-
         self._tokenizer.pre_tokenizer = pre_tokenizers.Sequence(
             [
                 pre_tokenizers.UnicodeScripts(),
                 pre_tokenizers.ByteLevel(add_prefix_space=False, use_regex=True),
             ]
         )
-
         self._tokenizer.decoder = decoders.ByteLevel()
         self._tokenizer.post_processor = processors.ByteLevel(trim_offsets=True)
 
-        if path is not None:
-            self._tokenizer = Tokenizer.from_file(path)
-
-    def _prepare_trainer(
-        self,
-        vocab_size: int,
-        min_freq: int,
-        reserved_token_size: int,
-        max_token_length=18,
-    ) -> tuple:
-        assert reserved_token_size > len(self._special_tokens)
-        reserved_tokens = [
-            f"<|reserve{i:02d}|>"
-            for i in range(reserved_token_size - len(self._special_tokens))
-        ]
-        detail_vocab_size = vocab_size - (
-            len(reserved_tokens) + len(self._special_tokens)
-        )
-
-        alphabet = pre_tokenizers.ByteLevel.alphabet()
-        min_size = len(alphabet) + len(self._control_tokens)
-        assert detail_vocab_size > min_size
-
-        trainer = BpeTrainer(
-            vocab_size=detail_vocab_size,
-            min_frequency=min_freq,
-            limit_alphabet=detail_vocab_size // 6,
-            max_token_length=max_token_length,
-            special_tokens=self._control_tokens,
-            initial_alphabet=alphabet,
-            show_progress=True,
-        )
-
-        return trainer, detail_vocab_size, reserved_tokens
-
-    def train(self, files, vocab_size, min_freq, reserved_token_size=100):
-        trainer, _, reserved_tokens = self._prepare_trainer(
-            vocab_size=vocab_size,
-            min_freq=min_freq,
-            reserved_token_size=reserved_token_size,
-        )
-        self._tokenizer.train(files=files, trainer=trainer)
-        self._tokenizer.add_special_tokens(self._special_tokens + reserved_tokens)
-
-    def train_from_iterator(
-        self, iterator, vocab_size, min_freq, reserved_token_size=100
-    ):
-        trainer, _, reserved_tokens = self._prepare_trainer(
-            vocab_size=vocab_size,
-            min_freq=min_freq,
-            reserved_token_size=reserved_token_size,
-        )
-        self._tokenizer.train_from_iterator(iterator=iterator, trainer=trainer)
-        self._tokenizer.add_special_tokens(self._special_tokens + reserved_tokens)
-
     def save(self, path):
         self._tokenizer.save(path)
 
@@ -94,12 +118,12 @@ class BpeTokenizer:
         add_special_tokens: bool = False,
     ) -> List:
         if isinstance(tokens, str):
-            encoded: Encoding = self._tokenizer.encode(
+            encoded = self._tokenizer.encode(
                 tokens, add_special_tokens=add_special_tokens
             )
             return encoded.ids if out_ids else encoded.tokens
-        elif isinstance(tokens, list):
-            encoded_list: List[Encoding] = self._tokenizer.encode_batch(
+        else:
+            encoded_list = self._tokenizer.encode_batch(
                 tokens, add_special_tokens=add_special_tokens
             )
             return [
@@ -115,17 +139,73 @@ class BpeTokenizer:
     @property
     def stop_ids(self) -> List[int]:
         stop_token = self._control_tokens + self._special_tokens
-        stop_ids = [self._tokenizer.token_to_id(token) for token in stop_token]
-        return stop_ids
+        return [self._tokenizer.token_to_id(tok) for tok in stop_token]
 
     @property
     def bos_id(self) -> int:
-        return self._tokenizer.token_to_id("<bos>")
+        return self._tokenizer.token_to_id(self._control_tokens[0])
 
     @property
     def eos_id(self) -> int:
-        return self._tokenizer.token_to_id("<eos>")
+        return self._tokenizer.token_to_id(self._control_tokens[1])
 
     @property
     def pad_id(self) -> int:
-        return self._tokenizer.token_to_id("<pad>")
+        return self._tokenizer.token_to_id(self._control_tokens[2])
+
+
+class BpeTrainer(BaseTrainer):
+    def __init__(self, tokenizer: BaseTokenizer):
+        super().__init__(tokenizer)
+
+    def _prepare_trainer(
+        self,
+        vocab_size: int,
+        min_freq: int,
+        reserved_token_size: int,
+        max_token_length=18,
+    ):
+        assert reserved_token_size > len(self.tokenizer._special_tokens)
+        reserved_tokens = [
+            f"<|reserve{i:02d}|>"
+            for i in range(reserved_token_size - len(self.tokenizer._special_tokens))
+        ]
+        detail_vocab_size = vocab_size - (
+            len(reserved_tokens) + len(self.tokenizer._special_tokens)
+        )
+        alphabet = pre_tokenizers.ByteLevel.alphabet()
+        min_size = len(alphabet) + len(self.tokenizer._control_tokens)
+        assert detail_vocab_size > min_size
+
+        trainer = BpeTrainerImpl(
+            vocab_size=detail_vocab_size,
+            min_frequency=min_freq,
+            limit_alphabet=detail_vocab_size // 6,
+            max_token_length=max_token_length,
+            special_tokens=self.tokenizer._control_tokens,
+            initial_alphabet=alphabet,
+            show_progress=True,
+        )
+        return trainer, reserved_tokens
+
+    def train(self, files, vocab_size, min_freq, reserved_token_size=100, **kwargs):
+        trainer, reserved_tokens = self._prepare_trainer(
+            vocab_size, min_freq, reserved_token_size, **kwargs
+        )
+        self.tokenizer._tokenizer.train(files=files, trainer=trainer)
+        self.tokenizer._tokenizer.add_special_tokens(
+            self.tokenizer._special_tokens + reserved_tokens
+        )
+
+    def train_from_iterator(
+        self, iterator, vocab_size, min_freq, reserved_token_size=100, **kwargs
+    ):
+        trainer, reserved_tokens = self._prepare_trainer(
+            vocab_size, min_freq, reserved_token_size, **kwargs
+        )
+        self.tokenizer._tokenizer.train_from_iterator(
+            iterator=iterator, trainer=trainer
+        )
+        self.tokenizer._tokenizer.add_special_tokens(
+            self.tokenizer._special_tokens + reserved_tokens
+        )
diff --git a/astrai/inference/generator.py b/astrai/inference/generator.py
index 89d10f3..2974c59 100644
--- a/astrai/inference/generator.py
+++ b/astrai/inference/generator.py
@@ -28,16 +28,16 @@ def build_prompt(
     result = ""
 
     if system_prompt:
-        result += f"<|im_start|>system\n{system_prompt}<|im_end|>\n"
+        result += f"<｜im▁start｜>system\n{system_prompt}<｜im▁end｜>\n"
 
     # (convert tuple format to ChatML)
     if history:
         for user_msg, assistant_msg in history:
-            result += f"<|im_start|>user\n{user_msg}<|im_end|>\n"
-            result += f"<|im_start|>assistant\n{assistant_msg}<|im_end|>\n"
+            result += f"<｜im▁start｜>user\n{user_msg}<｜im▁end｜>\n"
+            result += f"<｜im▁start｜>assistant\n{assistant_msg}<｜im▁end｜>\n"
 
-    result += f"<|im_start|>user\n{query}<|im_end|>\n"
-    result += "<|im_start|>assistant\n"
+    result += f"<｜im▁start｜>user\n{query}<｜im▁end｜>\n"
+    result += "<｜im▁start｜>assistant\n"
 
     return result