diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0f63f58..2504763 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -17,7 +17,16 @@ concurrency:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    name: build${{ matrix.arch == 'arm64' && ' (arm64)' || '' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - arch: amd64
+            runner: ubuntu-latest
+          - arch: arm64
+            runner: ubuntu-24.04-arm
+    runs-on: ${{ matrix.runner }}
     steps:
       - uses: actions/checkout@v7
 
@@ -40,7 +49,16 @@ jobs:
   # shards inside one launcher process, so the fork boundary and the summary/report
   # plumbing are invisible to it; this job is where they break loudly.
   coordinated-profile:
-    runs-on: ubuntu-latest
+    name: coordinated-profile${{ matrix.arch == 'arm64' && ' (arm64)' || '' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - arch: amd64
+            runner: ubuntu-latest
+          - arch: arm64
+            runner: ubuntu-24.04-arm
+    runs-on: ${{ matrix.runner }}
     steps:
       - uses: actions/checkout@v7
 
@@ -104,10 +122,24 @@ jobs:
   # registry needs -- no PAT. The smoke test boots the actual image: /healthz must answer
   # with a secret set, and an unset COORDINATOR_SECRETS must be a refused start.
   container-image:
-    runs-on: ubuntu-latest
+    name: container-image${{ matrix.arch == 'arm64' && ' (arm64)' || '' }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - arch: amd64
+            runner: ubuntu-latest
+          - arch: arm64
+            runner: ubuntu-24.04-arm
+    runs-on: ${{ matrix.runner }}
     permissions:
       contents: read
       packages: write
+    services:
+      registry:
+        image: registry:2
+        ports:
+          - 5000:5000
     steps:
       - uses: actions/checkout@v7
 
@@ -120,11 +152,20 @@ jobs:
             25
           cache: maven
 
-      - name: Build the coordinator app jar
-        run: mvn -B -ntp -DskipTests package
-
       - name: Build the image
-        run: docker build -t shard4j-coordinator-ci shard4j-coordinator
+        run: mvn -B -ntp -DskipTests package jib:dockerBuild -Djib.to.image=shard4j-coordinator-ci
+
+      - name: Check every platform is in the image index
+        if: matrix.arch == 'amd64'
+        run: |
+          mvn -B -ntp -DskipTests package jib:build -Djib.to.image=localhost:5000/shard4j-coordinator:ci \
+            -Djib.allowInsecureRegistries=true
+          platforms=$(docker buildx imagetools inspect localhost:5000/shard4j-coordinator:ci \
+            --format '{{range .Manifest.Manifests}}{{.Platform.OS}}/{{.Platform.Architecture}} {{end}}')
+          echo "platforms: $platforms"
+          for p in linux/amd64 linux/arm64 linux/ppc64le linux/s390x; do
+            case " $platforms " in *" $p "*) ;; *) echo "missing $p" >&2; exit 1 ;; esac
+          done
 
       - name: Smoke test the image
         run: |
@@ -162,18 +203,16 @@ jobs:
           fi
 
       - name: Push to GHCR
-        if: github.event_name == 'push'
+        if: github.event_name == 'push' && matrix.arch == 'amd64'
         run: |
           echo '${{ secrets.GITHUB_TOKEN }}' | docker login ghcr.io -u '${{ github.actor }}' --password-stdin
           IMAGE=ghcr.io/${{ github.repository }}
           VERSION=$(mvn -B -q help:evaluate -Dexpression=project.version -DforceStdout)
-          docker tag shard4j-coordinator-ci "$IMAGE:$VERSION"
-          docker push "$IMAGE:$VERSION"
+          tags=()
           if [ '${{ github.ref }}' = 'refs/heads/main' ]; then
-            docker tag shard4j-coordinator-ci "$IMAGE:sha-${GITHUB_SHA::12}"
-            docker push "$IMAGE:sha-${GITHUB_SHA::12}"
+            tags=(-Djib.to.tags="sha-${GITHUB_SHA::12}")
           fi
           if [ '${{ github.ref_type }}' = 'tag' ]; then
-            docker tag shard4j-coordinator-ci "$IMAGE:latest"
-            docker push "$IMAGE:latest"
+            tags=(-Djib.to.tags=latest)
           fi
+          mvn -B -ntp -DskipTests package jib:build -Djib.to.image="$IMAGE:$VERSION" "${tags[@]}"
diff --git a/pom.xml b/pom.xml
index 491078d..f00a6a4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -79,6 +79,9 @@
     <maven-javadoc-plugin.version>3.12.0</maven-javadoc-plugin.version>
     <maven-gpg-plugin.version>3.2.8</maven-gpg-plugin.version>
     <central-publishing-maven-plugin.version>0.11.0</central-publishing-maven-plugin.version>
+    <jib-maven-plugin.version>3.5.2</jib-maven-plugin.version>
+    <jib-ownership-extension-maven.version>0.1.0</jib-ownership-extension-maven.version>
+    <jib.skip>true</jib.skip>
     <gpg.keyname>D82FF933653EB8EC483709C77E738F7E2A355AAE</gpg.keyname>
 
     <rewrite-maven-plugin.version>6.46.1</rewrite-maven-plugin.version>
@@ -213,6 +216,11 @@
           <artifactId>spring-boot-maven-plugin</artifactId>
           <version>${spring-boot.version}</version>
         </plugin>
+        <plugin>
+          <groupId>com.google.cloud.tools</groupId>
+          <artifactId>jib-maven-plugin</artifactId>
+          <version>${jib-maven-plugin.version}</version>
+        </plugin>
       </plugins>
     </pluginManagement>
 
diff --git a/shard4j-coordinator/Dockerfile b/shard4j-coordinator/Dockerfile
deleted file mode 100644
index 8d9bdf3..0000000
--- a/shard4j-coordinator/Dockerfile
+++ /dev/null
@@ -1,23 +0,0 @@
-# The coordinator container: the Spring Boot repackaged app jar on the same JRE the
-# integration tests run it under. Build the jar first (`mvn -DskipTests package`), then
-# build with this module directory as the context.
-FROM eclipse-temurin:25-jre
-
-RUN groupadd --system --gid 10001 shard4j \
- && useradd --system --uid 10001 --gid shard4j --home-dir /opt/shard4j \
-      --shell /usr/sbin/nologin shard4j \
- && mkdir -p /opt/shard4j /data \
- && chown shard4j:shard4j /opt/shard4j /data
-
-COPY --chown=shard4j:shard4j target/shard4j-coordinator-*-app.jar /opt/shard4j/app.jar
-
-USER shard4j
-
-# The coordinator takes an exclusive lock on the data directory and appends JSONL there;
-# it must live on a mount, never in the container layer.
-ENV COORDINATOR_DATA_DIR=/data
-VOLUME /data
-
-EXPOSE 8080
-
-ENTRYPOINT ["java", "-jar", "/opt/shard4j/app.jar"]
diff --git a/shard4j-coordinator/pom.xml b/shard4j-coordinator/pom.xml
index d2ecc54..81c2572 100644
--- a/shard4j-coordinator/pom.xml
+++ b/shard4j-coordinator/pom.xml
@@ -20,6 +20,7 @@
          classpath, so it is free to sit on the current LTS. -->
     <maven.compiler.release>${coordinator.compiler.release}</maven.compiler.release>
     <rewrite.java.recipe>${coordinator.rewrite.java.recipe}</rewrite.java.recipe>
+    <jib.skip>false</jib.skip>
   </properties>
 
   <dependencies>
@@ -134,6 +135,81 @@
         </executions>
       </plugin>
 
+      <!-- Not bound to a phase: the everyday build stays offline. Jib assembles layers
+           instead of running RUN steps, so every platform the base image publishes is
+           a manifest entry, not an emulated build. -->
+      <plugin>
+        <groupId>com.google.cloud.tools</groupId>
+        <artifactId>jib-maven-plugin</artifactId>
+        <dependencies>
+          <dependency>
+            <groupId>com.google.cloud.tools</groupId>
+            <artifactId>jib-ownership-extension-maven</artifactId>
+            <version>${jib-ownership-extension-maven.version}</version>
+          </dependency>
+        </dependencies>
+        <configuration>
+          <from>
+            <image>eclipse-temurin:25-jre</image>
+            <platforms>
+              <platform>
+                <architecture>amd64</architecture>
+                <os>linux</os>
+              </platform>
+              <platform>
+                <architecture>arm64</architecture>
+                <os>linux</os>
+              </platform>
+              <platform>
+                <architecture>ppc64le</architecture>
+                <os>linux</os>
+              </platform>
+              <platform>
+                <architecture>s390x</architecture>
+                <os>linux</os>
+              </platform>
+            </platforms>
+          </from>
+          <to>
+            <image>shard4j-coordinator</image>
+          </to>
+          <extraDirectories>
+            <paths>
+              <path>
+                <from>src/main/jib</from>
+                <excludes>data/.keep</excludes>
+              </path>
+            </paths>
+          </extraDirectories>
+          <pluginExtensions>
+            <pluginExtension>
+              <implementation>com.google.cloud.tools.jib.maven.extension.ownership.JibOwnershipExtension</implementation>
+              <configuration implementation="com.google.cloud.tools.jib.maven.extension.ownership.Configuration">
+                <rules>
+                  <rule>
+                    <glob>/data</glob>
+                    <ownership>10001:10001</ownership>
+                  </rule>
+                </rules>
+              </configuration>
+            </pluginExtension>
+          </pluginExtensions>
+          <container>
+            <mainClass>com.marvinformatics.shard4j.coordinator.CoordinatorApplication</mainClass>
+            <user>10001:10001</user>
+            <ports>
+              <port>8080</port>
+            </ports>
+            <environment>
+              <COORDINATOR_DATA_DIR>/data</COORDINATOR_DATA_DIR>
+            </environment>
+            <volumes>
+              <volume>/data</volume>
+            </volumes>
+          </container>
+        </configuration>
+      </plugin>
+
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-failsafe-plugin</artifactId>
diff --git a/shard4j-coordinator/src/main/jib/data/.keep b/shard4j-coordinator/src/main/jib/data/.keep
new file mode 100644
index 0000000..e69de29