diff --git a/Jenkinsfile b/Jenkinsfile
index 1f3f4570..d142113b 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -84,6 +84,22 @@ def tools = [
       '''
     },
   ],
+  [
+    name: 'maven',
+    dockerfile: 'maven/3-jdk-21-debian.Dockerfile',
+    imageTag: '3-jdk-21-debian',
+    dependencySnapshotting: true,
+    testImageHook: {
+      sh '''
+        mvn -v
+        cat /etc/debian_version
+        # We explicitly approve updates of Debian to know what is going on.
+        grep "^11\\.8\\$" /etc/debian_version
+        test -e "$JAVA_HOME/bin/javac"
+        java -version 2>&1 | grep "openjdk version \\"21"
+      '''
+    },
+  ],
   [
     name: 'sonar-scanner',
     dependencySnapshotting: true,
diff --git a/README.md b/README.md
index ac94fcf6..014f63b7 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@ used in build pipelines.
 - [maven3-jdk-11-alpine](maven/)
 - [maven3-jdk-11-debian](maven/)
 - [maven3-jdk-17-debian](maven/)
+- [maven3-jdk-21-debian](maven/)
 - ~~[node12-alpine](node/)~~ (deprecated)
 - ~~[node14](node/)~~ (deprecated)
 - ~~[node14-browsers](node/)~~ (deprecated)
diff --git a/maven/3-jdk-21-debian.Dockerfile b/maven/3-jdk-21-debian.Dockerfile
new file mode 100644
index 00000000..a0572063
--- /dev/null
+++ b/maven/3-jdk-21-debian.Dockerfile
@@ -0,0 +1,38 @@
+FROM azul/zulu-openjdk-debian:21@sha256:b10a53a05c6fcdf4b27f83300e67e2c889883143c8164e8d8a2d0498ec254376
+
+RUN set -ex; \
+    apt-get update; \
+    apt-get install -y \
+      curl \
+      git \
+      jq \
+      openssh-client \
+      procps \
+      wget \
+      zip \
+      # Needed for `npm install keytar` for cals-cli.
+      libsecret-1-dev \
+      python3-pip \
+      python3-setuptools \
+      python3-wheel \
+    ; \
+    rm -rf /var/lib/apt/lists/*; \
+    \
+    # Install Node.
+    wget https://raw.githubusercontent.com/capralifecycle/buildtools-snippets/master/tools/node/install.sh -O /tmp/script.sh; \
+    sh /tmp/script.sh; \
+    rm /tmp/script.sh; \
+    node --version; \
+    npm --version; \
+    \
+    # Install Docker client.
+    wget https://raw.githubusercontent.com/capralifecycle/buildtools-snippets/master/tools/docker/install.sh -O- | sh; \
+    docker --version; \
+    \
+    # Install Maven.
+    wget https://raw.githubusercontent.com/capralifecycle/buildtools-snippets/master/tools/maven-3/install.sh -O- | sh; \
+    mvn -version; \
+    \
+    # Add a user with the UID that Jenkins will use during builds.
+    # This solves issues for some builds that require the user to exist.
+    useradd -u 1000 jenkins