diff --git a/src/cal/day06.rs b/src/cal/day06.rs
new file mode 100644
index 0000000..5c1bdc4
--- /dev/null
+++ b/src/cal/day06.rs
@@ -0,0 +1,23 @@
+use axum::{extract::Json, routing::post, Router};
+
+pub(crate) fn router() -> Router {
+    Router::new().route("/6", post(count_elf))
+}
+
+#[derive(serde::Serialize)]
+struct CountElf {
+    elf: usize,
+    elf_on_a_shelf: usize,
+    shelf_with_no_elf: usize,
+}
+
+async fn count_elf(body: String) -> Json<CountElf> {
+    let elf = body.matches("elf").count();
+    let elf_on_a_shelf = body.matches("elf on a shelf").count();
+    let shelf_with_no_elf = body.matches("shelf").count() - elf_on_a_shelf;
+    Json(CountElf {
+        elf,
+        elf_on_a_shelf,
+        shelf_with_no_elf,
+    })
+}
diff --git a/src/cal/mod.rs b/src/cal/mod.rs
index 52a3bd8..b302856 100644
--- a/src/cal/mod.rs
+++ b/src/cal/mod.rs
@@ -1,10 +1,12 @@
 mod day00;
 mod day01;
 mod day04;
+mod day06;
 
 pub(crate) fn router() -> axum::Router {
     axum::Router::new()
         .nest("/", day00::router())
         .nest("/", day01::router())
         .nest("/", day04::router())
+        .nest("/", day06::router())
 }