diff --git a/.gitignore b/.gitignore
index 1b6985c..f72df32 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,8 @@
+/.idea
+
 # Ignore Gradle project-specific cache directory
-.gradle
+/.gradle
 
 # Ignore Gradle build output directory
-build
+/build
+/app/build
diff --git a/.idea/compiler.xml b/.idea/compiler.xml
index b589d56..c515aca 100644
--- a/.idea/compiler.xml
+++ b/.idea/compiler.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="17" />
+    <bytecodeTargetLevel target="23" />
   </component>
-</project>
\ No newline at end of file
+</project>
diff --git a/.idea/gradle.xml b/.idea/gradle.xml
index 3ced4eb..8e890ae 100644
--- a/.idea/gradle.xml
+++ b/.idea/gradle.xml
@@ -4,8 +4,10 @@
   <component name="GradleSettings">
     <option name="linkedExternalProjectsSettings">
       <GradleProjectSettings>
+        <option name="distributionType" value="LOCAL" />
         <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="gradleJvm" value="#JAVA_HOME" />
+        <option name="gradleHome" value="/usr/lib/gradle" />
+        <option name="gradleJvm" value="usr-lib-jdk" />
         <option name="modules">
           <set>
             <option value="$PROJECT_DIR$" />
@@ -15,4 +17,4 @@
       </GradleProjectSettings>
     </option>
   </component>
-</project>
\ No newline at end of file
+</project>
diff --git a/.idea/misc.xml b/.idea/misc.xml
index 056a56f..a29a496 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,8 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="FrameworkDetectionExcludesConfiguration">
     <file type="web" url="file://$PROJECT_DIR$" />
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="jbr-17" project-jdk-type="JavaSDK" />
-</project>
\ No newline at end of file
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_X" project-jdk-name="jbr-17" project-jdk-type="JavaSDK" />
+</project>
diff --git a/README.md b/README.md
index 6806364..72131f6 100644
--- a/README.md
+++ b/README.md
@@ -4,13 +4,17 @@
 
 ### Setup
 
-Check which Java toolchains can be found by Gradle:
+Dependencies (JDK23, Gradle, IntelliJ) can be installed by running `nix-shell`.
+
+**Commandline**
+
+Check which Java toolchains Gradle finds:
 
 ```shell
 ./gradlew javaToolchains
 ```
 
-This should include version >= 17, e.g.:
+This should include version >= 23, e.g.:
 
 ```
  + N/A JDK 23-ga
@@ -22,6 +26,17 @@ This should include version >= 17, e.g.:
      | Detected by:        Current JVM
 ```
 
+**IntelliJ**
+
+When using `nix-shell`, some configuration is necessary:
+
+- STRG ALT SHIFT s -> SDK -> add JDK ->
+    - home path: /usr/lib/openjdk
+    - name: usr-lib-jdk
+- STRG ALT s -> build tools -> gradle ->
+    - local installation: /usr/lib/gradle
+    - Gradle JVM: usr-lib-jdk
+
 ### Tasks
 
 List all Gradle tasks which can be run:
diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index ab822aa..71687b0 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -28,7 +28,7 @@ dependencies {
 // Apply a specific Java toolchain to ease working on different environments.
 java {
     toolchain {
-        languageVersion = JavaLanguageVersion.of(17)
+        languageVersion = JavaLanguageVersion.of(23)
     }
 }
 
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..9a49d71
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,27 @@
+# Gradle's toolchain support does not work with IntelliJ, thus we have to use buildFHSUserEnv
+
+# https://discourse.nixos.org/t/how-to-create-a-development-environment-with-intellij-idea-and-openjdk/10153
+{
+  pkgs ? import <nixpkgs> {
+     # https://github.com/NixOS/nixpkgs/issues/166220#issuecomment-1745803058
+     config.allowUnfree = true;
+  }
+}:
+
+let
+  unstable = import (fetchTarball https://github.com/NixOS/nixpkgs/archive/nixos-unstable.tar.gz) { };
+  jdk = unstable.jdk23;
+  gradle = unstable.gradle;
+in
+
+(
+  pkgs.buildFHSUserEnv
+  {
+    name = "intellij-gradle-jdk23";
+    targetPkgs = pkgs_: [
+      pkgs_.jetbrains.idea-ultimate
+      jdk
+      gradle
+    ];
+  }
+).env