diff --git a/compiled_starters/csharp/codecrafters-http-server.csproj b/compiled_starters/csharp/codecrafters-http-server.csproj
index 70bd140..5812455 100644
--- a/compiled_starters/csharp/codecrafters-http-server.csproj
+++ b/compiled_starters/csharp/codecrafters-http-server.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <RootNamespace>codecrafters_http_server</RootNamespace>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
diff --git a/compiled_starters/csharp/codecrafters.yml b/compiled_starters/csharp/codecrafters.yml
index 80bc236..a8805bf 100644
--- a/compiled_starters/csharp/codecrafters.yml
+++ b/compiled_starters/csharp/codecrafters.yml
@@ -7,5 +7,5 @@ debug: false
 # Use this to change the C# version used to run your code
 # on Codecrafters.
 #
-# Available versions: dotnet-8.0
-language_pack: dotnet-8.0
+# Available versions: dotnet-9.0
+language_pack: dotnet-9.0
diff --git a/dockerfiles/dotnet-9.0.Dockerfile b/dockerfiles/dotnet-9.0.Dockerfile
new file mode 100644
index 0000000..5c1f25c
--- /dev/null
+++ b/dockerfiles/dotnet-9.0.Dockerfile
@@ -0,0 +1,17 @@
+# syntax=docker/dockerfile:1.7-labs
+FROM mcr.microsoft.com/dotnet/sdk:9.0-alpine
+
+WORKDIR /app
+
+# Re-build image if any of these files change
+ENV CODECRAFTERS_DEPENDENCY_FILE_PATHS="codecrafters-redis.csproj,codecrafters-redis.sln"
+
+# .git & README.md are unique per-repository. We ignore them on first copy to prevent cache misses
+COPY --exclude=.git --exclude=README.md . /app
+
+# This saves nuget packages to ~/.nuget
+RUN dotnet build --configuration Release .
+
+# Legacy support, remove in the next version of this dockerfile
+RUN echo "cd \${CODECRAFTERS_REPOSITORY_DIR} && dotnet build --configuration Release ." > /codecrafters-precompile.sh
+RUN chmod +x /codecrafters-precompile.sh
diff --git a/solutions/csharp/01-at4/code/codecrafters-http-server.csproj b/solutions/csharp/01-at4/code/codecrafters-http-server.csproj
index 70bd140..5812455 100644
--- a/solutions/csharp/01-at4/code/codecrafters-http-server.csproj
+++ b/solutions/csharp/01-at4/code/codecrafters-http-server.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <RootNamespace>codecrafters_http_server</RootNamespace>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
diff --git a/solutions/csharp/01-at4/code/codecrafters.yml b/solutions/csharp/01-at4/code/codecrafters.yml
index 80bc236..a8805bf 100644
--- a/solutions/csharp/01-at4/code/codecrafters.yml
+++ b/solutions/csharp/01-at4/code/codecrafters.yml
@@ -7,5 +7,5 @@ debug: false
 # Use this to change the C# version used to run your code
 # on Codecrafters.
 #
-# Available versions: dotnet-8.0
-language_pack: dotnet-8.0
+# Available versions: dotnet-9.0
+language_pack: dotnet-9.0
diff --git a/starter_templates/csharp/code/codecrafters-http-server.csproj b/starter_templates/csharp/code/codecrafters-http-server.csproj
index 70bd140..5812455 100644
--- a/starter_templates/csharp/code/codecrafters-http-server.csproj
+++ b/starter_templates/csharp/code/codecrafters-http-server.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <RootNamespace>codecrafters_http_server</RootNamespace>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>