diff --git a/src/cal/day00.rs b/src/cal/day00.rs
new file mode 100644
index 0000000..2d55dde
--- /dev/null
+++ b/src/cal/day00.rs
@@ -0,0 +1,15 @@
+use axum::{http::StatusCode, response::IntoResponse, routing::get, Router};
+
+pub(crate) fn router() -> Router {
+    Router::new()
+        .route("/", get(hello_world))
+        .route("/-1/error", get(fake_error))
+}
+
+async fn hello_world() -> impl IntoResponse {
+    "Hello, world!"
+}
+
+async fn fake_error() -> impl IntoResponse {
+    StatusCode::INTERNAL_SERVER_ERROR
+}
diff --git a/src/cal/mod.rs b/src/cal/mod.rs
new file mode 100644
index 0000000..a9dda0c
--- /dev/null
+++ b/src/cal/mod.rs
@@ -0,0 +1,6 @@
+mod day00;
+
+pub(crate) fn router() -> axum::Router {
+    axum::Router::new()
+        .nest("/", day00::router())
+}
diff --git a/src/main.rs b/src/main.rs
index c36b6b8..e54ff99 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,18 +1,6 @@
-use axum::{http::StatusCode, response::IntoResponse, routing::get, Router};
-
-async fn hello_world() -> impl IntoResponse {
-    "Hello, world!"
-}
-
-async fn fake_error() -> impl IntoResponse {
-    StatusCode::INTERNAL_SERVER_ERROR
-}
+mod cal;
 
 #[shuttle_runtime::main]
 async fn main() -> shuttle_axum::ShuttleAxum {
-    let router = Router::new()
-        .route("/", get(hello_world))
-        .route("/-1/error", get(fake_error));
-
-    Ok(router.into())
+    Ok(axum::Router::new().nest("/", cal::router()).into())
 }