diff --git a/python-api-examples/online-decode-files.py b/python-api-examples/online-decode-files.py
index fff8bf94..44fda24e 100755
--- a/python-api-examples/online-decode-files.py
+++ b/python-api-examples/online-decode-files.py
@@ -20,9 +20,10 @@ import argparse
 import time
 import wave
 from pathlib import Path
-from typing import Tuple
+from typing import List, Tuple
 
 import numpy as np
+import sentencepiece as spm
 import sherpa_onnx
 
 
@@ -69,6 +70,59 @@ def get_args():
         help="Valid values are greedy_search and modified_beam_search",
     )
 
+    parser.add_argument(
+        "--max-active-paths",
+        type=int,
+        default=4,
+        help="""Used only when --decoding-method is modified_beam_search.
+        It specifies number of active paths to keep during decoding.
+        """,
+    )
+
+    parser.add_argument(
+        "--bpe-model",
+        type=str,
+        default="",
+        help="""
+        Path to bpe.model, it will be used to tokenize contexts biasing phrases.
+        Used only when --decoding-method=modified_beam_search
+        """,
+    )
+
+    parser.add_argument(
+        "--modeling-unit",
+        type=str,
+        default="char",
+        help="""
+        The type of modeling unit, it will be used to tokenize contexts biasing phrases.
+        Valid values are bpe, bpe+char, char.
+        Note: the char here means characters in CJK languages.
+        Used only when --decoding-method=modified_beam_search
+        """,
+    )
+
+    parser.add_argument(
+        "--contexts",
+        type=str,
+        default="",
+        help="""
+        The context list, it is a string containing some words/phrases separated
+        with /, for example, 'HELLO WORLD/I LOVE YOU/GO AWAY".
+        Used only when --decoding-method=modified_beam_search
+        """,
+    )
+
+    parser.add_argument(
+        "--context-score",
+        type=float,
+        default=1.5,
+        help="""
+        The context score of each token for biasing word/phrase. Used only if
+        --contexts is given.
+        Used only when --decoding-method=modified_beam_search
+        """,
+    )
+
     parser.add_argument(
         "sound_files",
         type=str,
@@ -116,6 +170,27 @@ def read_wave(wave_filename: str) -> Tuple[np.ndarray, int]:
         return samples_float32, f.getframerate()
 
 
+def encode_contexts(args, contexts: List[str]) -> List[List[int]]:
+    sp = None
+    if "bpe" in args.modeling_unit:
+        assert_file_exists(args.bpe_model)
+        sp = spm.SentencePieceProcessor()
+        sp.load(args.bpe_model)
+    tokens = {}
+    with open(args.tokens, "r", encoding="utf-8") as f:
+        for line in f:
+            toks = line.strip().split()
+            assert len(toks) == 2, len(toks)
+            assert toks[0] not in tokens, f"Duplicate token: {toks} "
+            tokens[toks[0]] = int(toks[1])
+    return sherpa_onnx.encode_contexts(
+        modeling_unit=args.modeling_unit,
+        contexts=contexts,
+        sp=sp,
+        tokens_table=tokens,
+    )
+
+
 def main():
     args = get_args()
     assert_file_exists(args.encoder)
@@ -132,11 +207,20 @@ def main():
         sample_rate=16000,
         feature_dim=80,
         decoding_method=args.decoding_method,
+        max_active_paths=args.max_active_paths,
+        context_score=args.context_score,
     )
 
     print("Started!")
     start_time = time.time()
 
+    contexts_list = []
+    contexts = [x.strip().upper() for x in args.contexts.split("/") if x.strip()]
+    if contexts:
+        print(f"Contexts list: {contexts}")
+        contexts_list = encode_contexts(args, contexts)
+
+
     streams = []
     total_duration = 0
     for wave_filename in args.sound_files:
@@ -145,7 +229,11 @@ def main():
         duration = len(samples) / sample_rate
         total_duration += duration
 
-        s = recognizer.create_stream()
+        if contexts_list:
+            s = recognizer.create_stream(contexts_list=contexts_list)
+        else:
+            s = recognizer.create_stream()
+
         s.accept_waveform(sample_rate, samples)
 
         tail_paddings = np.zeros(int(0.2 * sample_rate), dtype=np.float32)
diff --git a/sherpa-onnx/csrc/online-recognizer.cc b/sherpa-onnx/csrc/online-recognizer.cc
index 06aab880..39d3c177 100644
--- a/sherpa-onnx/csrc/online-recognizer.cc
+++ b/sherpa-onnx/csrc/online-recognizer.cc
@@ -88,6 +88,9 @@ void OnlineRecognizerConfig::Register(ParseOptions *po) {
                "True to enable endpoint detection. False to disable it.");
   po->Register("max-active-paths", &max_active_paths,
                "beam size used in modified beam search.");
+  po->Register("context-score", &context_score,
+               "The bonus score for each token in context word/phrase. "
+               "Used only when decoding_method is modified_beam_search");
   po->Register("decoding-method", &decoding_method,
                "decoding method,"
                "now support greedy_search and modified_beam_search.");
@@ -115,6 +118,7 @@ std::string OnlineRecognizerConfig::ToString() const {
   os << "endpoint_config=" << endpoint_config.ToString() << ", ";
   os << "enable_endpoint=" << (enable_endpoint ? "True" : "False") << ", ";
   os << "max_active_paths=" << max_active_paths << ", ";
+  os << "context_score=" << context_score << ", ";
   os << "decoding_method=\"" << decoding_method << "\")";
 
   return os.str();
@@ -166,10 +170,37 @@ class OnlineRecognizer::Impl {
   }
 #endif
 
+  void InitOnlineStream(OnlineStream *stream) const {
+    auto r = decoder_->GetEmptyResult();
+
+    if (config_.decoding_method == "modified_beam_search" &&
+        nullptr != stream->GetContextGraph()) {
+      // r.hyps has only one element.
+      for (auto it = r.hyps.begin(); it != r.hyps.end(); ++it) {
+        it->second.context_state = stream->GetContextGraph()->Root();
+      }
+    }
+
+    stream->SetResult(r);
+    stream->SetStates(model_->GetEncoderInitStates());
+  }
+
   std::unique_ptr<OnlineStream> CreateStream() const {
     auto stream = std::make_unique<OnlineStream>(config_.feat_config);
-    stream->SetResult(decoder_->GetEmptyResult());
-    stream->SetStates(model_->GetEncoderInitStates());
+    InitOnlineStream(stream.get());
+    return stream;
+  }
+
+  std::unique_ptr<OnlineStream> CreateStream(
+      const std::vector<std::vector<int32_t>> &contexts) const {
+    // We create context_graph at this level, because we might have default
+    // context_graph(will be added later if needed) that belongs to the whole
+    // model rather than each stream.
+    auto context_graph =
+        std::make_shared<ContextGraph>(contexts, config_.context_score);
+    auto stream =
+        std::make_unique<OnlineStream>(config_.feat_config, context_graph);
+    InitOnlineStream(stream.get());
     return stream;
   }
 
@@ -188,8 +219,12 @@ class OnlineRecognizer::Impl {
     std::vector<float> features_vec(n * chunk_size * feature_dim);
     std::vector<std::vector<Ort::Value>> states_vec(n);
     std::vector<int64_t> all_processed_frames(n);
+    bool has_context_graph = false;
 
     for (int32_t i = 0; i != n; ++i) {
+      if (!has_context_graph && ss[i]->GetContextGraph())
+        has_context_graph = true;
+
       const auto num_processed_frames = ss[i]->GetNumProcessedFrames();
       std::vector<float> features =
           ss[i]->GetFrames(num_processed_frames, chunk_size);
@@ -226,7 +261,11 @@ class OnlineRecognizer::Impl {
     auto pair = model_->RunEncoder(std::move(x), std::move(states),
                                    std::move(processed_frames));
 
-    decoder_->Decode(std::move(pair.first), &results);
+    if (has_context_graph) {
+      decoder_->Decode(std::move(pair.first), ss, &results);
+    } else {
+      decoder_->Decode(std::move(pair.first), &results);
+    }
 
     std::vector<std::vector<Ort::Value>> next_states =
         model_->UnStackStates(pair.second);
@@ -297,6 +336,11 @@ std::unique_ptr<OnlineStream> OnlineRecognizer::CreateStream() const {
   return impl_->CreateStream();
 }
 
+std::unique_ptr<OnlineStream> OnlineRecognizer::CreateStream(
+    const std::vector<std::vector<int32_t>> &context_list) const {
+  return impl_->CreateStream(context_list);
+}
+
 bool OnlineRecognizer::IsReady(OnlineStream *s) const {
   return impl_->IsReady(s);
 }
diff --git a/sherpa-onnx/csrc/online-recognizer.h b/sherpa-onnx/csrc/online-recognizer.h
index 136fb820..bd8321c1 100644
--- a/sherpa-onnx/csrc/online-recognizer.h
+++ b/sherpa-onnx/csrc/online-recognizer.h
@@ -75,7 +75,10 @@ struct OnlineRecognizerConfig {
   std::string decoding_method = "greedy_search";
   // now support modified_beam_search and greedy_search
 
-  int32_t max_active_paths = 4;  // used only for modified_beam_search
+  // used only for modified_beam_search
+  int32_t max_active_paths = 4;
+  /// used only for modified_beam_search
+  float context_score = 1.5;
 
   OnlineRecognizerConfig() = default;
 
@@ -85,13 +88,14 @@ struct OnlineRecognizerConfig {
                          const EndpointConfig &endpoint_config,
                          bool enable_endpoint,
                          const std::string &decoding_method,
-                         int32_t max_active_paths)
+                         int32_t max_active_paths, float context_score)
       : feat_config(feat_config),
         model_config(model_config),
         endpoint_config(endpoint_config),
         enable_endpoint(enable_endpoint),
         decoding_method(decoding_method),
-        max_active_paths(max_active_paths) {}
+        max_active_paths(max_active_paths),
+        context_score(context_score) {}
 
   void Register(ParseOptions *po);
   bool Validate() const;
@@ -112,6 +116,10 @@ class OnlineRecognizer {
   /// Create a stream for decoding.
   std::unique_ptr<OnlineStream> CreateStream() const;
 
+  // Create a stream with context phrases
+  std::unique_ptr<OnlineStream> CreateStream(
+      const std::vector<std::vector<int32_t>> &context_list) const;
+
   /**
    * Return true if the given stream has enough frames for decoding.
    * Return false otherwise
diff --git a/sherpa-onnx/csrc/online-stream.cc b/sherpa-onnx/csrc/online-stream.cc
index 27c49462..e0593ff6 100644
--- a/sherpa-onnx/csrc/online-stream.cc
+++ b/sherpa-onnx/csrc/online-stream.cc
@@ -13,8 +13,9 @@ namespace sherpa_onnx {
 
 class OnlineStream::Impl {
  public:
-  explicit Impl(const FeatureExtractorConfig &config)
-      : feat_extractor_(config) {}
+  explicit Impl(const FeatureExtractorConfig &config,
+                ContextGraphPtr context_graph)
+      : feat_extractor_(config), context_graph_(context_graph) {}
 
   void AcceptWaveform(int32_t sampling_rate, const float *waveform, int32_t n) {
     feat_extractor_.AcceptWaveform(sampling_rate, waveform, n);
@@ -54,16 +55,21 @@ class OnlineStream::Impl {
 
   std::vector<Ort::Value> &GetStates() { return states_; }
 
+  const ContextGraphPtr &GetContextGraph() const { return context_graph_; }
+
  private:
   FeatureExtractor feat_extractor_;
+  /// For contextual-biasing
+  ContextGraphPtr context_graph_;
   int32_t num_processed_frames_ = 0;  // before subsampling
   int32_t start_frame_index_ = 0;     // never reset
   OnlineTransducerDecoderResult result_;
   std::vector<Ort::Value> states_;
 };
 
-OnlineStream::OnlineStream(const FeatureExtractorConfig &config /*= {}*/)
-    : impl_(std::make_unique<Impl>(config)) {}
+OnlineStream::OnlineStream(const FeatureExtractorConfig &config /*= {}*/,
+                           ContextGraphPtr context_graph /*= nullptr */)
+    : impl_(std::make_unique<Impl>(config, context_graph)) {}
 
 OnlineStream::~OnlineStream() = default;
 
@@ -109,4 +115,8 @@ std::vector<Ort::Value> &OnlineStream::GetStates() {
   return impl_->GetStates();
 }
 
+const ContextGraphPtr &OnlineStream::GetContextGraph() const {
+  return impl_->GetContextGraph();
+}
+
 }  // namespace sherpa_onnx
diff --git a/sherpa-onnx/csrc/online-stream.h b/sherpa-onnx/csrc/online-stream.h
index bc1935da..60dce950 100644
--- a/sherpa-onnx/csrc/online-stream.h
+++ b/sherpa-onnx/csrc/online-stream.h
@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "onnxruntime_cxx_api.h"  // NOLINT
+#include "sherpa-onnx/csrc/context-graph.h"
 #include "sherpa-onnx/csrc/features.h"
 #include "sherpa-onnx/csrc/online-transducer-decoder.h"
 
@@ -16,7 +17,8 @@ namespace sherpa_onnx {
 
 class OnlineStream {
  public:
-  explicit OnlineStream(const FeatureExtractorConfig &config = {});
+  explicit OnlineStream(const FeatureExtractorConfig &config = {},
+                        ContextGraphPtr context_graph = nullptr);
   ~OnlineStream();
 
   /**
@@ -71,6 +73,13 @@ class OnlineStream {
   void SetStates(std::vector<Ort::Value> states);
   std::vector<Ort::Value> &GetStates();
 
+  /**
+   * Get the context graph corresponding to this stream.
+   *
+   * @return Return the context graph for this stream.
+   */
+  const ContextGraphPtr &GetContextGraph() const;
+
  private:
   class Impl;
   std::unique_ptr<Impl> impl_;
diff --git a/sherpa-onnx/csrc/online-transducer-decoder.h b/sherpa-onnx/csrc/online-transducer-decoder.h
index dcfa363b..68a8fae4 100644
--- a/sherpa-onnx/csrc/online-transducer-decoder.h
+++ b/sherpa-onnx/csrc/online-transducer-decoder.h
@@ -9,6 +9,7 @@
 
 #include "onnxruntime_cxx_api.h"  // NOLINT
 #include "sherpa-onnx/csrc/hypothesis.h"
+#include "sherpa-onnx/csrc/macros.h"
 
 namespace sherpa_onnx {
 
@@ -45,6 +46,7 @@ struct OnlineTransducerDecoderResult {
       OnlineTransducerDecoderResult &&other);
 };
 
+class OnlineStream;
 class OnlineTransducerDecoder {
  public:
   virtual ~OnlineTransducerDecoder() = default;
@@ -76,6 +78,26 @@ class OnlineTransducerDecoder {
   virtual void Decode(Ort::Value encoder_out,
                       std::vector<OnlineTransducerDecoderResult> *result) = 0;
 
+  /** Run transducer beam search given the output from the encoder model.
+   *
+   * Note: Currently this interface is for contextual-biasing feature which
+   *       needs a ContextGraph owned by the OnlineStream.
+   *
+   * @param encoder_out A 3-D tensor of shape (N, T, joiner_dim)
+   * @param ss  A list of OnlineStreams.
+   * @param result  It is modified in-place.
+   *
+   * @note There is no need to pass encoder_out_length here since for the
+   * online decoding case, each utterance has the same number of frames
+   * and there are no paddings.
+   */
+  virtual void Decode(Ort::Value encoder_out, OnlineStream **ss,
+                      std::vector<OnlineTransducerDecoderResult> *result) {
+    SHERPA_ONNX_LOGE(
+        "This interface is for OnlineTransducerModifiedBeamSearchDecoder.");
+    exit(-1);
+  }
+
   // used for endpointing. We need to keep decoder_out after reset
   virtual void UpdateDecoderOut(OnlineTransducerDecoderResult *result) {}
 };
diff --git a/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.cc b/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.cc
index cbf01a0a..7e2a4a97 100644
--- a/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.cc
+++ b/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.cc
@@ -9,6 +9,7 @@
 #include <utility>
 #include <vector>
 
+#include "sherpa-onnx/csrc/log.h"
 #include "sherpa-onnx/csrc/onnx-utils.h"
 
 namespace sherpa_onnx {
@@ -62,6 +63,12 @@ void OnlineTransducerModifiedBeamSearchDecoder::StripLeadingBlanks(
 void OnlineTransducerModifiedBeamSearchDecoder::Decode(
     Ort::Value encoder_out,
     std::vector<OnlineTransducerDecoderResult> *result) {
+  Decode(std::move(encoder_out), nullptr, result);
+}
+
+void OnlineTransducerModifiedBeamSearchDecoder::Decode(
+    Ort::Value encoder_out, OnlineStream **ss,
+    std::vector<OnlineTransducerDecoderResult> *result) {
   std::vector<int64_t> encoder_out_shape =
       encoder_out.GetTensorTypeAndShapeInfo().GetShape();
 
@@ -74,6 +81,7 @@ void OnlineTransducerModifiedBeamSearchDecoder::Decode(
   }
 
   int32_t batch_size = static_cast<int32_t>(encoder_out_shape[0]);
+
   int32_t num_frames = static_cast<int32_t>(encoder_out_shape[1]);
   int32_t vocab_size = model_->VocabSize();
 
@@ -142,18 +150,27 @@ void OnlineTransducerModifiedBeamSearchDecoder::Decode(
 
         Hypothesis new_hyp = prev[hyp_index];
         const float prev_lm_log_prob = new_hyp.lm_log_prob;
+        float context_score = 0;
+        auto context_state = new_hyp.context_state;
+
         if (new_token != 0) {
           new_hyp.ys.push_back(new_token);
           new_hyp.timestamps.push_back(t + frame_offset);
           new_hyp.num_trailing_blanks = 0;
+          if (ss != nullptr && ss[b]->GetContextGraph() != nullptr) {
+            auto context_res = ss[b]->GetContextGraph()->ForwardOneStep(
+                context_state, new_token);
+            context_score = context_res.first;
+            new_hyp.context_state = context_res.second;
+          }
           if (lm_) {
             lm_->ComputeLMScore(lm_scale_, &new_hyp);
           }
         } else {
           ++new_hyp.num_trailing_blanks;
         }
-        new_hyp.log_prob =
-            p_logprob[k] - prev_lm_log_prob;  // log_prob only includes the
+        new_hyp.log_prob = p_logprob[k] + context_score -
+                           prev_lm_log_prob;  // log_prob only includes the
                                               // score of the transducer
         hyps.Add(std::move(new_hyp));
       }  // for (auto k : topk)
diff --git a/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.h b/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.h
index 5fbf6a31..d05c5167 100644
--- a/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.h
+++ b/sherpa-onnx/csrc/online-transducer-modified-beam-search-decoder.h
@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "sherpa-onnx/csrc/online-lm.h"
+#include "sherpa-onnx/csrc/online-stream.h"
 #include "sherpa-onnx/csrc/online-transducer-decoder.h"
 #include "sherpa-onnx/csrc/online-transducer-model.h"
 
@@ -33,6 +34,9 @@ class OnlineTransducerModifiedBeamSearchDecoder
   void Decode(Ort::Value encoder_out,
               std::vector<OnlineTransducerDecoderResult> *result) override;
 
+  void Decode(Ort::Value encoder_out, OnlineStream **ss,
+              std::vector<OnlineTransducerDecoderResult> *result) override;
+
   void UpdateDecoderOut(OnlineTransducerDecoderResult *result) override;
 
  private:
diff --git a/sherpa-onnx/python/csrc/online-recognizer.cc b/sherpa-onnx/python/csrc/online-recognizer.cc
index 54d97e80..02ab95e6 100644
--- a/sherpa-onnx/python/csrc/online-recognizer.cc
+++ b/sherpa-onnx/python/csrc/online-recognizer.cc
@@ -22,18 +22,19 @@ static void PybindOnlineRecognizerConfig(py::module *m) {
   py::class_<PyClass>(*m, "OnlineRecognizerConfig")
       .def(py::init<const FeatureExtractorConfig &,
                     const OnlineTransducerModelConfig &, const OnlineLMConfig &,
-                    const EndpointConfig &, bool, const std::string &,
-                    int32_t>(),
+                    const EndpointConfig &, bool, const std::string &, int32_t,
+                    float>(),
            py::arg("feat_config"), py::arg("model_config"),
            py::arg("lm_config") = OnlineLMConfig(), py::arg("endpoint_config"),
            py::arg("enable_endpoint"), py::arg("decoding_method"),
-           py::arg("max_active_paths"))
+           py::arg("max_active_paths"), py::arg("context_score"))
       .def_readwrite("feat_config", &PyClass::feat_config)
       .def_readwrite("model_config", &PyClass::model_config)
       .def_readwrite("endpoint_config", &PyClass::endpoint_config)
       .def_readwrite("enable_endpoint", &PyClass::enable_endpoint)
       .def_readwrite("decoding_method", &PyClass::decoding_method)
       .def_readwrite("max_active_paths", &PyClass::max_active_paths)
+      .def_readwrite("context_score", &PyClass::context_score)
       .def("__str__", &PyClass::ToString);
 }
 
@@ -44,7 +45,15 @@ void PybindOnlineRecognizer(py::module *m) {
   using PyClass = OnlineRecognizer;
   py::class_<PyClass>(*m, "OnlineRecognizer")
       .def(py::init<const OnlineRecognizerConfig &>(), py::arg("config"))
-      .def("create_stream", &PyClass::CreateStream)
+      .def("create_stream",
+           [](const PyClass &self) { return self.CreateStream(); })
+      .def(
+          "create_stream",
+          [](PyClass &self,
+             const std::vector<std::vector<int32_t>> &contexts_list) {
+            return self.CreateStream(contexts_list);
+          },
+          py::arg("contexts_list"))
       .def("is_ready", &PyClass::IsReady)
       .def("decode_stream", &PyClass::DecodeStream)
       .def("decode_streams",
diff --git a/sherpa-onnx/python/sherpa_onnx/online_recognizer.py b/sherpa-onnx/python/sherpa_onnx/online_recognizer.py
index 48dc74e7..c981bc04 100644
--- a/sherpa-onnx/python/sherpa_onnx/online_recognizer.py
+++ b/sherpa-onnx/python/sherpa_onnx/online_recognizer.py
@@ -1,6 +1,6 @@
 # Copyright (c)  2023  Xiaomi Corporation
 from pathlib import Path
-from typing import List
+from typing import List, Optional
 
 from _sherpa_onnx import (
     EndpointConfig,
@@ -39,6 +39,7 @@ class OnlineRecognizer(object):
         rule3_min_utterance_length: float = 20.0,
         decoding_method: str = "greedy_search",
         max_active_paths: int = 4,
+        context_score: float = 1.5,
         provider: str = "cpu",
     ):
         """
@@ -124,13 +125,17 @@ class OnlineRecognizer(object):
             enable_endpoint=enable_endpoint_detection,
             decoding_method=decoding_method,
             max_active_paths=max_active_paths,
+            context_score=context_score,
         )
 
         self.recognizer = _Recognizer(recognizer_config)
         self.config = recognizer_config
 
-    def create_stream(self):
-        return self.recognizer.create_stream()
+    def create_stream(self, contexts_list : Optional[List[List[int]]] = None):
+        if contexts_list is None:
+            return self.recognizer.create_stream()
+        else:
+            return self.recognizer.create_stream(contexts_list)
 
     def decode_stream(self, s: OnlineStream):
         self.recognizer.decode_stream(s)