diff --git a/_doc/examples/plot_quantization.py b/_doc/examples/plot_quantization.py
new file mode 100644
index 0000000..54a52a3
--- /dev/null
+++ b/_doc/examples/plot_quantization.py
@@ -0,0 +1,262 @@
+"""
+.. _l-plot-quantization:
+
+==============================
+Quantization with onnxruntime
+=============================
+
+.. index:: quantization, onnxruntime
+
+Quantization aims at reducing the model size but it does
+compute the output at a lower precision too.
+The static quantization estimates the best quantization parameters
+for every observation in a dataset. The dynamic quantization
+estimates these parameters for every observation at inference time.
+Let's see the differences
+(see alse `Quantize ONNX Models
+<https://onnxruntime.ai/docs/performance/quantization.html>`_).
+
+
+.. contents::
+    :local:
+
+A model
+=======
+
+Let's retrieve a not so big model. They are taken from the
+`ONNX Model Zoo <https://github.com/onnx/models>`_ or can even be custom.
+"""
+import os
+import urllib.request
+import time
+import tqdm
+import numpy
+import onnx
+import pandas
+import matplotlib.pyplot as plt
+from onnxruntime import InferenceSession
+from onnxruntime.quantization.quantize import quantize_dynamic, quantize_static
+from onnxruntime.quantization.calibrate import CalibrationDataReader
+from onnxruntime.quantization.quant_utils import QuantFormat, QuantType
+from onnxruntime.quantization.shape_inference import quant_pre_process
+
+
+def download_file(url, name, min_size):
+    if not os.path.exists(name):
+        print(f"download '{url}'")
+        with urllib.request.urlopen(url) as u:
+            content = u.read()
+        if len(content) < min_size:
+            raise RuntimeError(
+                f"Unable to download '{url}' due to\n{content}")
+        print(f"downloaded {len(content)} bytes.")
+        with open(name, "wb") as f:
+            f.write(content)
+    else:
+        print(f"'{name}' already downloaded")
+
+
+small = "small"
+if small:
+    model_name = "mobilenetv2-12.onnx"
+    url_name = ("https://github.com/onnx/models/raw/main/vision/"
+                "classification/mobilenet/model")
+else:
+    model_name = "resnet50-v1-12.onnx"
+    url_name = ("https://github.com/onnx/models/raw/main/vision/"
+                "classification/resnet/model")
+
+if url_name is not None:
+    url_name += "/" + model_name
+    download_file(url_name, model_name, 100000)
+
+#############################
+# Inputs and outputs.
+
+sess_full = InferenceSession(model_name, providers=["CPUExecutionProvider"])
+
+for i in sess_full.get_inputs():
+    print(f"input {i}, name={i.name!r}, type={i.type}, shape={i.shape}")
+    input_name = i.name
+    input_shape = list(i.shape)
+    if input_shape[0] in [None, "batch_size", "N"]:
+        input_shape[0] = 1
+
+output_name = None
+for i in sess_full.get_outputs():
+    print(f"output {i}, name={i.name!r}, type={i.type}, shape={i.shape}")
+    if output_name is None:
+        output_name = i.name
+
+print(f"input_name={input_name!r}, output_name={output_name!r}")
+
+################################
+# We build random data.
+
+maxN = 50
+imgs = [numpy.random.rand(*input_shape).astype(numpy.float32)
+        for i in range(maxN)]
+
+experiments = []
+
+#############################################
+# Static Quantization
+# ===================
+#
+# This quantization estimates the best quantization parameters
+# (scale and bias) to minimize an error compare to the original
+# model. It requires data.
+
+
+class DataReader(CalibrationDataReader):
+    def __init__(self, input_name, imgs):
+        self.input_name = input_name
+        self.data = imgs
+        self.pos = -1
+
+    def get_next(self):
+        if self.pos >= len(self.data) - 1:
+            return None
+        self.pos += 1
+        return {self.input_name: self.data[self.pos]}
+
+    def rewind(self):
+        self.pos = -1
+
+##############################
+# Runs the quantization.
+
+
+quantize_name = model_name + ".qdq.onnx"
+
+
+quantize_static(model_name,
+                quantize_name,
+                calibration_data_reader=DataReader(input_name, imgs),
+                quant_format=QuantFormat.QDQ)
+
+####################################
+# Compares the size.
+
+with open(model_name, "rb") as f:
+    model_onnx = onnx.load(f)
+with open(quantize_name, "rb") as f:
+    quant_onnx = onnx.load(f)
+
+model_onnx_bytes = model_onnx.SerializeToString()
+quant_onnx_bytes = quant_onnx.SerializeToString()
+
+print(f"Model size: {len(model_onnx_bytes)} and "
+      f"quantized: {len(quant_onnx_bytes)}, "
+      f"ratio={len(quant_onnx_bytes) / len(model_onnx_bytes)}.")
+
+##########################################
+# Let's measure the dIscrepancies.
+
+
+def compare_with(sess_full, imgs, quantize_name):
+    sess = InferenceSession(quantize_name, providers=["CPUExecutionProvider"])
+
+    mean_diff = 0
+    mean_max = 0
+    time_full = 0
+    time_quant = 0
+    disa = 0
+
+    for img in tqdm.tqdm(imgs):
+        feeds = {input_name: img}
+
+        begin = time.perf_counter()
+        full = sess_full.run(None, feeds)
+        time_full += time.perf_counter() - begin
+
+        begin = time.perf_counter()
+        quant = sess.run(None, feeds)
+        time_quant += time.perf_counter() - begin
+
+        diff = numpy.abs(full[0] - quant[0]).ravel()
+        mean_max += numpy.abs(full[0].ravel().max() - quant[0].ravel().max())
+        mean_diff += diff.mean()
+        if full[0].argmax() != quant[0].argmax():
+            disa += 1
+
+    mean_diff /= len(imgs)
+    mean_max /= len(imgs)
+    time_full /= len(imgs)
+    time_quant /= len(imgs)
+    return dict(mean_diff=mean_diff, mean_max=mean_max,
+                time_full=time_full, time_quant=time_quant,
+                disagree=disa / len(imgs),
+                ratio=time_quant / time_full)
+
+
+res = compare_with(sess_full, imgs, quantize_name)
+res["name"] = "static"
+experiments.append(res)
+print(f"Discrepancies: mean={res['mean_diff']:.2f}, "
+      f"mean_max={res['mean_max']:.2f}, "
+      f"times {res['time_full']} -> {res['time_quant']}, "
+      f"disagreement={res['disagree']:.2f}")
+res
+
+#######################################
+# With preprocessing
+# ==================
+
+preprocessed_name = model_name + ".pre.onnx"
+
+quant_pre_process(model_name, preprocessed_name)
+
+#################################
+# And quantization again.
+
+quantize_static(preprocessed_name,
+                quantize_name,
+                calibration_data_reader=DataReader(input_name, imgs),
+                quant_format=QuantFormat.QDQ)
+
+res = compare_with(sess_full, imgs, quantize_name)
+res["name"] = "static-pre"
+experiments.append(res)
+print(f"Discrepancies: mean={res['mean_diff']:.2f}, "
+      f"mean_max={res['mean_max']:.2f}, "
+      f"times {res['time_full']} -> {res['time_quant']}, "
+      f"disagreement={res['disagree']:.2f}")
+res
+
+#########################################
+# Dynamic quantization
+# ====================
+
+quantize_name = model_name + ".qdq.dyn.onnx"
+
+quantize_dynamic(preprocessed_name, quantize_name,
+                 weight_type=QuantType.QUInt8)
+
+res = compare_with(sess_full, imgs, quantize_name)
+res["name"] = "dynamic"
+experiments.append(res)
+print(f"Discrepancies: mean={res['mean_diff']:.2f}, "
+      f"mean_max={res['mean_max']:.2f}, "
+      f"times {res['time_full']} -> {res['time_quant']}, "
+      f"disagreement={res['disagree']:.2f}")
+res
+
+#######################################
+# Conclusion
+# ==========
+#
+# The static quantization (same quantized parameters for all observations)
+# is not really working. The quantized
+# model disagrees on almost all observations. Dynamic quantization
+# (quantized parameters different for each observation)
+# is a lot better but a lot slower too.
+
+fig, ax = plt.subplots(1, 3, figsize=(12, 4))
+df = pandas.DataFrame(experiments).set_index("name")
+df[["ratio"]].plot(ax=ax[0], title="Speedup\nlower better", kind="bar")
+df[["mean_diff"]].plot(ax=ax[1], title="Average difference", kind="bar")
+df[["disagree"]].plot(
+    ax=ax[2], title="Proportion bast class is the same", kind="bar")
+
+# plt.show()
diff --git a/_doc/sphinxdoc/source/api/onnxruntime_python/index.rst b/_doc/sphinxdoc/source/api/onnxruntime_python/index.rst
index e8ade2c..338f0ce 100644
--- a/_doc/sphinxdoc/source/api/onnxruntime_python/index.rst
+++ b/_doc/sphinxdoc/source/api/onnxruntime_python/index.rst
@@ -27,3 +27,4 @@ It is recommended to use C classes in that case
     training_torch
     exceptions
     grad
+    tools
diff --git a/_doc/sphinxdoc/source/api/onnxruntime_python/tools.rst b/_doc/sphinxdoc/source/api/onnxruntime_python/tools.rst
new file mode 100644
index 0000000..4af4c09
--- /dev/null
+++ b/_doc/sphinxdoc/source/api/onnxruntime_python/tools.rst
@@ -0,0 +1,34 @@
+
+=====
+Tools
+=====
+
+.. contents::
+    :local:
+
+Quantization
+============
+
+The main functions.
+
+.. autofunction:: onnxruntime.quantization.quantize.quantize_dynamic
+
+.. autofunction:: onnxruntime.quantization.quantize.quantize_static
+
+.. autofunction:: onnxruntime.quantization.shape_inference.quant_pre_process
+
+Calibration:
+
+.. autoclass:: onnxruntime.quantization.calibrate.CalibrationDataReader
+    :members:
+
+The parameters.
+
+.. autoclass:: onnxruntime.quantization.quant_utils.QuantFormat
+    :members:
+
+.. autoclass:: onnxruntime.quantization.quant_utils.QuantizationMode
+    :members:
+
+.. autoclass:: onnxruntime.quantization.quant_utils.QuantType
+    :members:
diff --git a/_doc/sphinxdoc/source/blog/2022/2022-12-02_wsl.rst b/_doc/sphinxdoc/source/blog/2022/2022-12-02_wsl.rst
index 4a6a260..5afacaf 100644
--- a/_doc/sphinxdoc/source/blog/2022/2022-12-02_wsl.rst
+++ b/_doc/sphinxdoc/source/blog/2022/2022-12-02_wsl.rst
@@ -54,7 +54,7 @@
     Installation of `ninja <https://github.com/ninja-build/ninja/>`_:
 
     ::
-    
+
         wget https://github.com/ninja-build/ninja/releases/download/v1.11.1/ninja-linux.zip
         unzip ninja-linux.zip
         sudo cp ./ninja /usr/local/bin/
@@ -132,7 +132,7 @@
     Otherwise, it has to be built from sources:
 
     ::
-    
+
         wget https://repo.anaconda.com/archive/Anaconda3-2022.10-Linux-x86_64.sh
         bash Anaconda3-2022.10-Linux-x86_64.sh
         conda create -p ~/install/acond10 python=3.10
@@ -165,7 +165,7 @@
         import torch
         print(torch.cuda.is_available())
 
-    Build :epkg:`onnxruntime-training` before :epkg:`onnx` 
+    Build :epkg:`onnxruntime-training` before :epkg:`onnx`
     to build :epkg:`protobuf` as well.
 
     ::
diff --git a/_doc/sphinxdoc/source/conf.py b/_doc/sphinxdoc/source/conf.py
index 2a4b435..31ab807 100644
--- a/_doc/sphinxdoc/source/conf.py
+++ b/_doc/sphinxdoc/source/conf.py
@@ -146,6 +146,7 @@ def callback_begin():
     'ONNX ML Operators':
         'https://github.com/onnx/onnx/blob/master/docs/Operators-ml.md',
     'ONNX Zoo': 'https://github.com/onnx/models',
+    'onnxcustom': 'http://www.xavierdupre.fr/app/onnxcustom/helpsphinx/',
     'onnxmltools': 'https://github.com/onnx/onnxmltools',
     'onnxruntime': 'https://microsoft.github.io/onnxruntime/',
     'onnxruntime-extensions':
diff --git a/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/index.rst b/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/index.rst
index f2086de..a0113e7 100644
--- a/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/index.rst
+++ b/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/index.rst
@@ -17,3 +17,4 @@ available on many other platforms.
     inference
     training_ort_api
     extensions
+    quantization
diff --git a/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/quantization.rst b/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/quantization.rst
new file mode 100644
index 0000000..38506c8
--- /dev/null
+++ b/_doc/sphinxdoc/source/tutorials/tutorial_onnxruntime/quantization.rst
@@ -0,0 +1,18 @@
+
+=============================
+Quantization with onnxruntime
+=============================
+
+.. contents::
+    :local:
+
+Simple case
+===========
+
+Examples
+========
+
+.. toctree::
+    :maxdepth: 1
+
+    ../../gyexamples/plot_quantization
diff --git a/_doc/sphinxdoc/source/tutorials/tutorial_skl/tutorial_4_complex.rst b/_doc/sphinxdoc/source/tutorials/tutorial_skl/tutorial_4_complex.rst
index d2451a8..123787d 100644
--- a/_doc/sphinxdoc/source/tutorials/tutorial_skl/tutorial_4_complex.rst
+++ b/_doc/sphinxdoc/source/tutorials/tutorial_skl/tutorial_4_complex.rst
@@ -21,4 +21,5 @@ Unexpected issues
 
     ../../gyexamples/plot_usparse_xgboost
     ../../gyexamples/plot_gexternal_lightgbm_reg
+    ../../gyexamples/plot_gexternal_lightgbm_reg_per
     ../../gyexamples/plot_transformer_discrepancy