diff --git a/operators/string_utils.cc b/operators/string_utils_onnx.cc
similarity index 99%
rename from operators/string_utils.cc
rename to operators/string_utils_onnx.cc
index ecb6713..91dbe76 100644
--- a/operators/string_utils.cc
+++ b/operators/string_utils_onnx.cc
@@ -2,7 +2,7 @@
 #include "farmhash.h"
 #endif
 
-#include "string_utils.h"
+#include "string_utils_onnx.h"
 
 std::vector<std::string_view> SplitString(const std::string_view& str, const std::string_view& seps, bool remove_empty_entries) {
   std::vector<std::string_view> result;
diff --git a/operators/string_utils.h b/operators/string_utils_onnx.h
similarity index 89%
rename from operators/string_utils.h
rename to operators/string_utils_onnx.h
index 5653fbd..6556666 100644
--- a/operators/string_utils.h
+++ b/operators/string_utils_onnx.h
@@ -4,7 +4,6 @@
 #include <iostream>
 #include <sstream>
 #include <vector>
-#include "ocos.h"
 
 template <typename T>
 inline void MakeStringInternal(std::ostringstream& ss, const T& t) noexcept {
@@ -23,11 +22,6 @@ inline void MakeStringInternal(std::ostringstream& ss, const std::vector<int64_t
   ss << "]";
 }
 
-template <>
-inline void MakeStringInternal(std::ostringstream& ss, const OrtTensorDimensions& t) noexcept {
-  MakeStringInternal(ss, static_cast<const std::vector<int64_t>&>(t));
-}
-
 template <>
 inline void MakeStringInternal(std::ostringstream& ss, const std::vector<std::string>& t) noexcept {
   ss << "[";
diff --git a/operators/tokenizer/basic_tokenizer.cc b/operators/tokenizer/basic_tokenizer.cc
index 324a774..00eac2b 100644
--- a/operators/tokenizer/basic_tokenizer.cc
+++ b/operators/tokenizer/basic_tokenizer.cc
@@ -1,9 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
-#include "string_utils.h"
+#include "string_utils_onnx.h"
 #include "basic_tokenizer.hpp"
-#include "string_tensor.h"
 #include <vector>
 #include <locale>
 #include <codecvt>
@@ -81,52 +80,3 @@ std::vector<ustring> BasicTokenizer::Tokenize(ustring text) {
   push_current_token_and_clear();
   return result;
 }
-
-KernelBasicTokenizer::KernelBasicTokenizer(const OrtApi& api, const OrtKernelInfo* info) : BaseKernel(api, info) {
-  bool do_lower_case = TryToGetAttributeWithDefault("do_lower_case", true);
-  bool tokenize_chinese_chars = TryToGetAttributeWithDefault("tokenize_chinese_chars", true);
-  bool strip_accents = TryToGetAttributeWithDefault("strip_accents", false);
-  bool tokenize_punctuation = TryToGetAttributeWithDefault("tokenize_punctuation", false);
-  bool remove_control_chars = TryToGetAttributeWithDefault("remove_control_chars", true);
-
-  tokenizer_ = std::make_shared<BasicTokenizer>(do_lower_case, tokenize_chinese_chars, strip_accents, tokenize_punctuation, remove_control_chars);
-}
-
-void KernelBasicTokenizer::Compute(OrtKernelContext* context) {
-  // Setup inputs
-  const OrtValue* input = ort_.KernelContext_GetInput(context, 0);
-  std::vector<std::string> input_data;
-  GetTensorMutableDataString(api_, ort_, context, input, input_data);
-
-  OrtTensorDimensions dimensions(ort_, input);
-  if (dimensions.size() != 1 && dimensions[0] != 1) {
-    ORTX_CXX_API_THROW("[BasicTokenizer]: only support string scalar.", ORT_INVALID_GRAPH);
-  }
-
-  OrtValue* output = ort_.KernelContext_GetOutput(context, 0, dimensions.data(), dimensions.size());
-  std::vector<ustring> result = tokenizer_->Tokenize(ustring(input_data[0]));
-
-  FillTensorDataString(api_, ort_, context, result, output);
-}
-
-void* CustomOpBasicTokenizer::CreateKernel(const OrtApi& api, const OrtKernelInfo* info) const {
-  return CreateKernelImpl(api, info);
-};
-
-const char* CustomOpBasicTokenizer::GetName() const { return "BasicTokenizer"; };
-
-size_t CustomOpBasicTokenizer::GetInputTypeCount() const {
-  return 1;
-};
-
-ONNXTensorElementDataType CustomOpBasicTokenizer::GetInputType(size_t /*index*/) const {
-  return ONNX_TENSOR_ELEMENT_DATA_TYPE_STRING;
-};
-
-size_t CustomOpBasicTokenizer::GetOutputTypeCount() const {
-  return 1;
-};
-
-ONNXTensorElementDataType CustomOpBasicTokenizer::GetOutputType(size_t /*index*/) const {
-  return ONNX_TENSOR_ELEMENT_DATA_TYPE_STRING;
-};
diff --git a/operators/tokenizer/basic_tokenizer.hpp b/operators/tokenizer/basic_tokenizer.hpp
index 046499e..9fd6f1a 100644
--- a/operators/tokenizer/basic_tokenizer.hpp
+++ b/operators/tokenizer/basic_tokenizer.hpp
@@ -3,8 +3,7 @@
 
 #pragma once
 
-#include "ocos.h"
-#include "string_utils.h"
+#include "string_utils_onnx.h"
 #include "ustring.h"
 
 class BasicTokenizer {
@@ -19,19 +18,3 @@ class BasicTokenizer {
   bool tokenize_punctuation_;
   bool remove_control_chars_;
 };
-
-struct KernelBasicTokenizer : BaseKernel {
-  KernelBasicTokenizer(const OrtApi& api, const OrtKernelInfo* info);
-  void Compute(OrtKernelContext* context);
- private:
-  std::shared_ptr<BasicTokenizer> tokenizer_;
-};
-
-struct CustomOpBasicTokenizer : OrtW::CustomOpBase<CustomOpBasicTokenizer, KernelBasicTokenizer> {
-  void* CreateKernel(const OrtApi& api, const OrtKernelInfo* info) const;
-  const char* GetName() const;
-  size_t GetInputTypeCount() const;
-  ONNXTensorElementDataType GetInputType(size_t index) const;
-  size_t GetOutputTypeCount() const;
-  ONNXTensorElementDataType GetOutputType(size_t index) const;
-};
diff --git a/operators/tokenizer/bert_tokenizer.cc b/operators/tokenizer/bert_tokenizer.cc
index b860ba6..9f43c5e 100644
--- a/operators/tokenizer/bert_tokenizer.cc
+++ b/operators/tokenizer/bert_tokenizer.cc
@@ -33,7 +33,8 @@ int32_t BertTokenizerVocab::FindTokenId(const ustring& token) {
 
   auto it = vocab_.find(utf8_token);
   if (it == vocab_.end()) {
-    ORTX_CXX_API_THROW("[BertTokenizerVocab]: can not find tokens: " + std::string(token), ORT_RUNTIME_EXCEPTION);
+    std::cout << "[BertTokenizerVocab]: can not find tokens: " + std::string(token);
+    return -1;
   }
 
   return it->second;
@@ -276,138 +277,3 @@ TruncateStrategy::TruncateStrategy(std::string_view strategy_name) : strategy_(T
   }
 }
 
-KernelBertTokenizer::KernelBertTokenizer(const OrtApi& api, const OrtKernelInfo* info) : BaseKernel(api, info) {
-  std::string vocab = ort_.KernelInfoGetAttribute<std::string>(info, "vocab_file");
-  bool do_lower_case = TryToGetAttributeWithDefault("do_lower_case", true);
-  bool do_basic_tokenize = TryToGetAttributeWithDefault("do_basic_tokenize", true);
-  std::string unk_token = TryToGetAttributeWithDefault("unk_token", std::string("[UNK]"));
-  std::string sep_token = TryToGetAttributeWithDefault("sep_token", std::string("[SEP]"));
-  std::string pad_token = TryToGetAttributeWithDefault("pad_token", std::string("[PAD]"));
-  std::string cls_token = TryToGetAttributeWithDefault("cls_token", std::string("[CLS]"));
-  std::string mask_token = TryToGetAttributeWithDefault("mask_token", std::string("[MASK]"));
-  bool tokenize_chinese_chars = TryToGetAttributeWithDefault("tokenize_chinese_chars", true);
-  bool strip_accents = TryToGetAttributeWithDefault("strip_accents", false);
-  std::string suffix_indicator = TryToGetAttributeWithDefault("suffix_indicator", std::string("##"));
-  std::string truncation_strategy_name = TryToGetAttributeWithDefault("truncation_strategy_name", std::string("longest_first"));
-  int32_t max_len = static_cast<int32_t>(TryToGetAttributeWithDefault("max_length", int64_t(-1)));
-
-  tokenizer_ = std::make_unique<BertTokenizer>(
-    vocab, do_lower_case, do_basic_tokenize, ustring(unk_token),
-    ustring(sep_token), ustring(pad_token), ustring(cls_token),
-    ustring(mask_token), tokenize_chinese_chars, strip_accents,
-    ustring(suffix_indicator), max_len, truncation_strategy_name);
-}
-
-void KernelBertTokenizer::Compute(OrtKernelContext* context) {
-  // Setup inputs
-  const OrtValue* input = ort_.KernelContext_GetInput(context, 0);
-  std::vector<std::string> input_data;
-  GetTensorMutableDataString(api_, ort_, context, input, input_data);
-
-  if (input_data.size() != 1 && input_data.size() != 2) {
-    ORTX_CXX_API_THROW("[BertTokenizer]: only support one or two query.", ORT_INVALID_GRAPH);
-  }
-  std::vector<int64_t> input_ids;
-  std::vector<int64_t> token_type_ids;
-
-  if (input_data.size() == 1) {
-    std::vector<ustring> tokens = tokenizer_->Tokenize(ustring(input_data[0]));
-    std::vector<int64_t> encoded = tokenizer_->Encode(tokens);
-    tokenizer_->Truncate(encoded);
-    input_ids = tokenizer_->AddSpecialToken(encoded);
-    token_type_ids = tokenizer_->GenerateTypeId(encoded);
-  } else {
-    std::vector<ustring> tokens1 = tokenizer_->Tokenize(ustring(input_data[0]));
-    std::vector<ustring> tokens2 = tokenizer_->Tokenize(ustring(input_data[1]));
-    std::vector<int64_t> encoded1 = tokenizer_->Encode(tokens1);
-    std::vector<int64_t> encoded2 = tokenizer_->Encode(tokens2);
-    input_ids = tokenizer_->AddSpecialToken(encoded1, encoded2);
-    token_type_ids = tokenizer_->GenerateTypeId(encoded1, encoded2);
-  }
-
-  std::vector<int64_t> attention_mask(input_ids.size(), 1);
-
-  std::vector<int64_t> output_dim{static_cast<int64_t>(input_ids.size())};
-
-  SetOutput(context, 0, output_dim, input_ids);
-  SetOutput(context, 1, output_dim, token_type_ids);
-  SetOutput(context, 2, output_dim, attention_mask);
-}
-
-void* CustomOpBertTokenizer::CreateKernel(const OrtApi& api, const OrtKernelInfo* info) const {
-  return CreateKernelImpl(api, info);
-}
-
-const char* CustomOpBertTokenizer::GetName() const { return "BertTokenizer"; }
-
-size_t CustomOpBertTokenizer::GetInputTypeCount() const {
-  return 1;
-}
-
-ONNXTensorElementDataType CustomOpBertTokenizer::GetInputType(size_t /* index */) const {
-  return ONNX_TENSOR_ELEMENT_DATA_TYPE_STRING;
-}
-
-size_t CustomOpBertTokenizer::GetOutputTypeCount() const {
-  return 3;
-}
-
-ONNXTensorElementDataType CustomOpBertTokenizer::GetOutputType(size_t /* index */) const {
-  return ONNX_TENSOR_ELEMENT_DATA_TYPE_INT64;
-}
-
-KernelHfBertTokenizer::KernelHfBertTokenizer(const OrtApi& api, const OrtKernelInfo* info) : KernelBertTokenizer(api, info) {}
-
-void KernelHfBertTokenizer::Compute(OrtKernelContext* context) {
-  // Setup inputs
-  const OrtValue *const input = ort_.KernelContext_GetInput(context, 0);
-  std::vector<std::string> input_data;
-  GetTensorMutableDataString(api_, ort_, context, input, input_data);
-
-  if (input_data.size() != 2) {
-    ORTX_CXX_API_THROW("[HfBertTokenizer]: Support only two input strings.", ORT_INVALID_GRAPH);
-  }
-
-  std::vector<ustring> tokens1 = tokenizer_->Tokenize(ustring(input_data[0]));
-  std::vector<ustring> tokens2 = tokenizer_->Tokenize(ustring(input_data[1]));
-  std::vector<int64_t> encoded1 = tokenizer_->Encode(tokens1);
-  std::vector<int64_t> encoded2 = tokenizer_->Encode(tokens2);
-  std::vector<int64_t> input_ids = tokenizer_->AddSpecialToken(encoded1, encoded2);
-  std::vector<int64_t> token_type_ids = tokenizer_->GenerateTypeId(encoded1, encoded2);
-  std::vector<int64_t> attention_mask(input_ids.size(), 1LL);
-
-  const std::vector<int64_t> outer_dims{1LL, static_cast<int64_t>(input_ids.size())};
-  const std::vector<int64_t> inner_dims{1LL};
-  for (int32_t i = 0; i < 3; ++i) {
-    OrtValue* const value = ort_.KernelContext_GetOutput(context, i, outer_dims.data(), outer_dims.size());
-    OrtTensorTypeAndShapeInfo *const info = ort_.GetTensorTypeAndShape(value);
-    ort_.SetDimensions(info, inner_dims.data(), inner_dims.size());
-    ort_.ReleaseTensorTypeAndShapeInfo(info);
-  }
-
-  SetOutput(context, 0, outer_dims, input_ids);
-  SetOutput(context, 1, outer_dims, attention_mask);
-  SetOutput(context, 2, outer_dims, token_type_ids);
-}
-
-void* CustomOpHfBertTokenizer::CreateKernel(const OrtApi& api, const OrtKernelInfo* info) const {
-  return CreateKernelImpl(api, info);
-}
-
-const char* CustomOpHfBertTokenizer::GetName() const { return "HfBertTokenizer"; }
-
-size_t CustomOpHfBertTokenizer::GetInputTypeCount() const {
-  return 1;
-}
-
-ONNXTensorElementDataType CustomOpHfBertTokenizer::GetInputType(size_t /* index */) const {
-  return ONNX_TENSOR_ELEMENT_DATA_TYPE_STRING;
-}
-
-size_t CustomOpHfBertTokenizer::GetOutputTypeCount() const {
-  return 3;
-}
-
-ONNXTensorElementDataType CustomOpHfBertTokenizer::GetOutputType(size_t /* index */) const {
-  return ONNX_TENSOR_ELEMENT_DATA_TYPE_INT64;
-}
diff --git a/operators/tokenizer/bert_tokenizer.hpp b/operators/tokenizer/bert_tokenizer.hpp
index 6dfcd84..10565e4 100644
--- a/operators/tokenizer/bert_tokenizer.hpp
+++ b/operators/tokenizer/bert_tokenizer.hpp
@@ -3,12 +3,11 @@
 
 #pragma once
 
+#include <memory>
 #include <unordered_map>
 #include <vector>
-#include "ocos.h"
 #include "ustring.h"
-#include "string_utils.h"
-#include "string_tensor.h"
+#include "string_utils_onnx.h"
 #include "basic_tokenizer.hpp"
 
 class BertTokenizerVocab final {
@@ -89,33 +88,4 @@ class BertTokenizer final {
   std::unique_ptr<WordpieceTokenizer> wordpiece_tokenizer_;
 };
 
-struct KernelBertTokenizer : BaseKernel {
-  KernelBertTokenizer(const OrtApi& api, const OrtKernelInfo* info);
-  void Compute(OrtKernelContext* context);
 
- protected:
-  std::unique_ptr<BertTokenizer> tokenizer_;
-};
-
-struct CustomOpBertTokenizer : OrtW::CustomOpBase<CustomOpBertTokenizer, KernelBertTokenizer> {
-  void* CreateKernel(const OrtApi& api, const OrtKernelInfo* info) const;
-  const char* GetName() const;
-  size_t GetInputTypeCount() const;
-  ONNXTensorElementDataType GetInputType(size_t index) const;
-  size_t GetOutputTypeCount() const;
-  ONNXTensorElementDataType GetOutputType(size_t index) const;
-};
-
-struct KernelHfBertTokenizer : KernelBertTokenizer {
-  KernelHfBertTokenizer(const OrtApi& api, const OrtKernelInfo* info);
-  void Compute(OrtKernelContext* context);
-};
-
-struct CustomOpHfBertTokenizer : OrtW::CustomOpBase<CustomOpHfBertTokenizer, KernelHfBertTokenizer> {
-  void* CreateKernel(const OrtApi& api, const OrtKernelInfo* info) const;
-  const char* GetName() const;
-  size_t GetInputTypeCount() const;
-  ONNXTensorElementDataType GetInputType(size_t index) const;
-  size_t GetOutputTypeCount() const;
-  ONNXTensorElementDataType GetOutputType(size_t index) const;
-};