diff --git a/.java-version b/.java-version
index 2dbc24b3..aabe6ec3 100644
--- a/.java-version
+++ b/.java-version
@@ -1 +1 @@
-11.0
+21
diff --git a/build.sbt b/build.sbt
index 26aa3908..477ba92c 100644
--- a/build.sbt
+++ b/build.sbt
@@ -194,7 +194,7 @@ lazy val backend = (project in file("backend"))
     IntTest / testOptions := Seq(Tests.Filter(itFilter)),
     RoutesKeys.routesImport += "utils.Binders._",
     playDefaultPort := port,
-    debianPackageDependencies := Seq("java-11-amazon-corretto-jdk"),
+    debianPackageDependencies := Seq("java-21-amazon-corretto-jdk"),
     Linux / maintainer := "Guardian Developers <dig.dev.software@theguardian.com>",
     Linux / packageSummary := description.value,
     packageDescription := description.value,
@@ -204,10 +204,9 @@ lazy val backend = (project in file("backend"))
     Universal / javaOptions ++= Seq(
       "-Dpidfile.path=/dev/null",
       "-Dcom.amazonaws.sdk.enableDefaultMetrics=cloudwatchRegion=eu-west-1",
-      "-J-XX:MaxRAMFraction=2",
-      "-J-XX:InitialRAMFraction=2",
-      "-J-XX:MaxMetaspaceSize=500m",
-      "-J-XX:+UseConcMarkSweepGC",
+      "-J-XX:MaxRAMPercentage=50",
+      "-J-XX:InitialRAMPercentage=50",
+      "-J-XX:+UseG1GC",
       "-J-Xlog:gc*",
       "-J-XX:+HeapDumpOnOutOfMemoryError",
       s"-J-Xloggc:/var/log/${name.value}/gc.log",