diff --git a/tools/doc/cpp.doxy.in b/tools/doc/cpp.doxy.in
index 1a6c921a1a..e994d787c7 100644
--- a/tools/doc/cpp.doxy.in
+++ b/tools/doc/cpp.doxy.in
@@ -1356,7 +1356,7 @@ CHM_FILE               =
 HHC_LOCATION           =
 
 # The GENERATE_CHI flag controls if a separate .chi index file is generated
-# (YES) or that it should be included in the master .chm file (NO).
+# (YES) or that it should be included in the main .chm file (NO).
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTMLHELP is set to YES.
 
diff --git a/tools/doc/dotnet.doxy.in b/tools/doc/dotnet.doxy.in
index 4434841a1c..dfe28afcc6 100644
--- a/tools/doc/dotnet.doxy.in
+++ b/tools/doc/dotnet.doxy.in
@@ -1337,7 +1337,7 @@ CHM_FILE               =
 HHC_LOCATION           =
 
 # The GENERATE_CHI flag controls if a separate .chi index file is generated
-# (YES) or that it should be included in the master .chm file (NO).
+# (YES) or that it should be included in the main .chm file (NO).
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTMLHELP is set to YES.
 
diff --git a/tools/doc/java.doxy.in b/tools/doc/java.doxy.in
index 4f2bab8313..7d33df1bfe 100644
--- a/tools/doc/java.doxy.in
+++ b/tools/doc/java.doxy.in
@@ -1337,7 +1337,7 @@ CHM_FILE               =
 HHC_LOCATION           =
 
 # The GENERATE_CHI flag controls if a separate .chi index file is generated
-# (YES) or that it should be included in the master .chm file (NO).
+# (YES) or that it should be included in the main .chm file (NO).
 # The default value is: NO.
 # This tag requires that the tag GENERATE_HTMLHELP is set to YES.
 
diff --git a/tools/docker/images/alpine-edge.Dockerfile b/tools/docker/images/alpine-edge.Dockerfile
index e7a6975997..2fa155b6a4 100644
--- a/tools/docker/images/alpine-edge.Dockerfile
+++ b/tools/docker/images/alpine-edge.Dockerfile
@@ -56,7 +56,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/centos-7.Dockerfile b/tools/docker/images/centos-7.Dockerfile
index 12e955080c..f1aa755b3f 100644
--- a/tools/docker/images/centos-7.Dockerfile
+++ b/tools/docker/images/centos-7.Dockerfile
@@ -70,7 +70,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/centos-8.Dockerfile b/tools/docker/images/centos-8.Dockerfile
index 62928acdea..3da49b5c53 100644
--- a/tools/docker/images/centos-8.Dockerfile
+++ b/tools/docker/images/centos-8.Dockerfile
@@ -63,7 +63,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/debian-10.Dockerfile b/tools/docker/images/debian-10.Dockerfile
index ae7df17725..332b2bcda1 100644
--- a/tools/docker/images/debian-10.Dockerfile
+++ b/tools/docker/images/debian-10.Dockerfile
@@ -53,7 +53,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/debian-11.Dockerfile b/tools/docker/images/debian-11.Dockerfile
index 92d62d5ce7..e55251815f 100644
--- a/tools/docker/images/debian-11.Dockerfile
+++ b/tools/docker/images/debian-11.Dockerfile
@@ -53,7 +53,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/fedora-33.Dockerfile b/tools/docker/images/fedora-33.Dockerfile
index c1677d7f8f..3c14a6e176 100644
--- a/tools/docker/images/fedora-33.Dockerfile
+++ b/tools/docker/images/fedora-33.Dockerfile
@@ -52,7 +52,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/fedora-34.Dockerfile b/tools/docker/images/fedora-34.Dockerfile
index 5ada2e12df..8704804487 100644
--- a/tools/docker/images/fedora-34.Dockerfile
+++ b/tools/docker/images/fedora-34.Dockerfile
@@ -52,7 +52,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/fedora-35.Dockerfile b/tools/docker/images/fedora-35.Dockerfile
index f111a559d6..78dc0a4dc0 100644
--- a/tools/docker/images/fedora-35.Dockerfile
+++ b/tools/docker/images/fedora-35.Dockerfile
@@ -52,7 +52,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/opensuse-leap.Dockerfile b/tools/docker/images/opensuse-leap.Dockerfile
index a6d612b227..547bac7278 100644
--- a/tools/docker/images/opensuse-leap.Dockerfile
+++ b/tools/docker/images/opensuse-leap.Dockerfile
@@ -73,7 +73,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/ubuntu-18.04.Dockerfile b/tools/docker/images/ubuntu-18.04.Dockerfile
index c2025f96e7..f390d659e5 100644
--- a/tools/docker/images/ubuntu-18.04.Dockerfile
+++ b/tools/docker/images/ubuntu-18.04.Dockerfile
@@ -65,7 +65,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/ubuntu-20.04.Dockerfile b/tools/docker/images/ubuntu-20.04.Dockerfile
index d7d063142c..4a38f4837c 100644
--- a/tools/docker/images/ubuntu-20.04.Dockerfile
+++ b/tools/docker/images/ubuntu-20.04.Dockerfile
@@ -58,7 +58,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/images/ubuntu-22.04.Dockerfile b/tools/docker/images/ubuntu-22.04.Dockerfile
index eee54f1cd7..fd9ded1ff2 100644
--- a/tools/docker/images/ubuntu-22.04.Dockerfile
+++ b/tools/docker/images/ubuntu-22.04.Dockerfile
@@ -53,7 +53,7 @@ COPY or-tools.snk /root/or-tools.snk
 ENV DOTNET_SNK=/root/or-tools.snk
 
 ARG SRC_GIT_BRANCH
-ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-master}
+ENV SRC_GIT_BRANCH ${SRC_GIT_BRANCH:-main}
 ARG SRC_GIT_SHA1
 ENV SRC_GIT_SHA1 ${SRC_GIT_SHA1:-unknown}
 
diff --git a/tools/docker/minizinc-challenge.Dockerfile b/tools/docker/minizinc-challenge.Dockerfile
index 423a2e0699..292692b21d 100644
--- a/tools/docker/minizinc-challenge.Dockerfile
+++ b/tools/docker/minizinc-challenge.Dockerfile
@@ -1,6 +1,6 @@
 FROM minizinc/mznc2021:latest AS env
 
-ENV SRC_GIT_BRANCH master
+ENV SRC_GIT_BRANCH main
 
 ENV TZ=America/Los_Angeles
 RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
diff --git a/tools/docker/python/amd64/alpine.Dockerfile b/tools/docker/python/amd64/alpine.Dockerfile
index 6bb6c9d140..cdbabb9b05 100644
--- a/tools/docker/python/amd64/alpine.Dockerfile
+++ b/tools/docker/python/amd64/alpine.Dockerfile
@@ -23,7 +23,7 @@ FROM env AS devel
 ENV GIT_URL https://github.com/google/or-tools
 
 ARG GIT_BRANCH
-ENV GIT_BRANCH ${GIT_BRANCH:-master}
+ENV GIT_BRANCH ${GIT_BRANCH:-main}
 ARG GIT_SHA1
 ENV GIT_SHA1 ${GIT_SHA1:-unknown}
 
diff --git a/tools/docker/python/amd64/manylinux.Dockerfile b/tools/docker/python/amd64/manylinux.Dockerfile
index 1294e8976c..97a5d5f183 100644
--- a/tools/docker/python/amd64/manylinux.Dockerfile
+++ b/tools/docker/python/amd64/manylinux.Dockerfile
@@ -51,7 +51,7 @@ FROM env AS devel
 ENV GIT_URL https://github.com/google/or-tools
 
 ARG GIT_BRANCH
-ENV GIT_BRANCH ${GIT_BRANCH:-master}
+ENV GIT_BRANCH ${GIT_BRANCH:-main}
 ARG GIT_SHA1
 ENV GIT_SHA1 ${GIT_SHA1:-unknown}
 
diff --git a/tools/docker/python/arm64v8/alpine.Dockerfile b/tools/docker/python/arm64v8/alpine.Dockerfile
index 64f0247e9c..7a4b453c07 100644
--- a/tools/docker/python/arm64v8/alpine.Dockerfile
+++ b/tools/docker/python/arm64v8/alpine.Dockerfile
@@ -22,7 +22,7 @@ FROM env AS devel
 ENV GIT_URL https://github.com/google/or-tools
 
 ARG GIT_BRANCH
-ENV GIT_BRANCH ${GIT_BRANCH:-master}
+ENV GIT_BRANCH ${GIT_BRANCH:-main}
 ARG GIT_SHA1
 ENV GIT_SHA1 ${GIT_SHA1:-unknown}
 
diff --git a/tools/docker/python/arm64v8/manylinux.Dockerfile b/tools/docker/python/arm64v8/manylinux.Dockerfile
index a2783e254e..13842aa918 100644
--- a/tools/docker/python/arm64v8/manylinux.Dockerfile
+++ b/tools/docker/python/arm64v8/manylinux.Dockerfile
@@ -53,7 +53,7 @@ FROM env AS devel
 ENV GIT_URL https://github.com/google/or-tools
 
 ARG GIT_BRANCH
-ENV GIT_BRANCH ${GIT_BRANCH:-master}
+ENV GIT_BRANCH ${GIT_BRANCH:-main}
 ARG GIT_SHA1
 ENV GIT_SHA1 ${GIT_SHA1:-unknown}
 
diff --git a/tools/export_to_ipynb.py b/tools/export_to_ipynb.py
index 90c385406b..531e4e0339 100755
--- a/tools/export_to_ipynb.py
+++ b/tools/export_to_ipynb.py
@@ -52,11 +52,11 @@ basename = '# ' + os.path.basename(input_file).replace('.py', '')
 nbook['cells'].append(v4.new_markdown_cell(source=basename, id='basename'))
 
 print('Adding link cell...')
-github_logo = 'https://raw.githubusercontent.com/google/or-tools/master/tools/github_32px.png'
-github_path = 'https://github.com/google/or-tools/blob/master/' + input_file
+github_logo = 'https://raw.githubusercontent.com/google/or-tools/main/tools/github_32px.png'
+github_path = 'https://github.com/google/or-tools/blob/main/' + input_file
 
-colab_path = 'https://colab.research.google.com/github/google/or-tools/blob/master/' + output_file
-colab_logo = 'https://raw.githubusercontent.com/google/or-tools/master/tools/colab_32px.png'
+colab_path = 'https://colab.research.google.com/github/google/or-tools/blob/main/' + output_file
+colab_logo = 'https://raw.githubusercontent.com/google/or-tools/main/tools/colab_32px.png'
 link = f'''<table align=\"left\">
 <td>
 <a href=\"{colab_path}\"><img src=\"{colab_logo}\"/>Run in Google Colab</a>
diff --git a/tools/release/Dockerfile b/tools/release/Dockerfile
index 1d113856a1..fc57a7e50b 100644
--- a/tools/release/Dockerfile
+++ b/tools/release/Dockerfile
@@ -78,7 +78,7 @@ WORKDIR /root
 # use ORTOOLS_GIT_SHA1 to modify the command
 # i.e. avoid docker reusing the cache when new commit is pushed
 ARG ORTOOLS_GIT_BRANCH
-ENV ORTOOLS_GIT_BRANCH ${ORTOOLS_GIT_BRANCH:-master}
+ENV ORTOOLS_GIT_BRANCH ${ORTOOLS_GIT_BRANCH:-main}
 ARG ORTOOLS_GIT_SHA1
 ENV ORTOOLS_GIT_SHA1 ${ORTOOLS_GIT_SHA1:-unknown}
 RUN git clone -b "${ORTOOLS_GIT_BRANCH}" --single-branch https://github.com/google/or-tools \