diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 000000000..0b89ab829
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,42 @@
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+  schedule:
+    - cron: "25 11 * * 0"
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ javascript, java ]
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v2
+        with:
+          languages: ${{ matrix.language }}
+          queries: +security-and-quality
+
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@v2
+        if: ${{ matrix.language == 'javascript' || matrix.language == 'java' }}
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v2
+        with:
+          category: "/language:${{ matrix.language }}"
diff --git a/server/build.gradle b/server/build.gradle
index 07f36da6e..985ec2bf5 100644
--- a/server/build.gradle
+++ b/server/build.gradle
@@ -12,10 +12,10 @@ plugins {
   id 'checkstyle'
 }
 
-// Build and run the project with Java 11
+// Build and run the project with Java 21
 java {
   toolchain {
-    languageVersion = JavaLanguageVersion.of(11)
+    languageVersion = JavaLanguageVersion.of(21)
   }
 }
 
@@ -46,6 +46,9 @@ dependencies {
   // JUnit Jupiter Engine for testing.
   testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.10.1'
 
+  // JUnit Platform Launcher for testing.
+  testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
+
   // Mockito for testing
   testImplementation 'org.mockito:mockito-core:5.8.0'
 
@@ -75,7 +78,7 @@ jacocoTestReport {
     // This isn't strictly necessary, but the default reports
     // location is buried pretty deep in the build directory,
     // so this makes it easier to find.
-    html.destination file("${buildDir}/jacocoHtml")
+    html.outputLocation = file("${buildDir}/jacocoHtml")
   }
 
   afterEvaluate {
diff --git a/server/settings.gradle b/server/settings.gradle
index 0e6c57337..e5443ab65 100644
--- a/server/settings.gradle
+++ b/server/settings.gradle
@@ -6,6 +6,13 @@
  * Detailed information about configuring a multi-project build in Gradle can be found
  * in the user manual at https://docs.gradle.org/5.6/userguide/multi_project_builds.html
  */
+// This allows us to use the jresolver plugin. If we have
+// this plugin in place, we can specify a particular JDK version
+// in `build.gradle` and Gradle will download it for us if it's
+// not already installed on the system. This will hopefully make
+// it easier for people to run the project on a broad range of
+// computers without having to worry about installing the right
+// JDK version.
 
 plugins {
     id 'org.gradle.toolchains.foojay-resolver-convention' version '0.7.0'