diff --git a/Cargo.lock b/Cargo.lock
index f5bee1d..bd5cbe4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -431,9 +431,11 @@ dependencies = [
  "base64",
  "chrono",
  "image",
+ "regex",
  "reqwest",
  "serde",
  "serde_json",
+ "sha256",
  "shuttle-axum",
  "shuttle-runtime",
  "shuttle-shared-db",
@@ -2541,6 +2543,19 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "sha256"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7895c8ae88588ccead14ff438b939b0c569cd619116f14b4d13fdff7b8333386"
+dependencies = [
+ "async-trait",
+ "bytes",
+ "hex",
+ "sha2",
+ "tokio",
+]
+
 [[package]]
 name = "sharded-slab"
 version = "0.1.7"
diff --git a/Cargo.toml b/Cargo.toml
index f4bbdc9..22c718f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,9 +11,11 @@ axum-extra = { version = "0.9.0", features = ["typed-header"] }
 base64 = "0.21.5"
 chrono = { version = "0.4.31", default-features = false, features = ["std"] }
 image = "0.24.7"
+regex = "1.10.2"
 reqwest = { version = "0.11.22", features = ["json"] }
 serde = { version = "1.0.193", features = ["derive"] }
 serde_json = "1.0.108"
+sha256 = "1.4.0"
 shuttle-axum = { version = "0.35.0", default-features = false, features = ["axum-0-7"] }
 shuttle-runtime = "0.35.0"
 shuttle-shared-db = { version = "0.35.1", features = ["postgres"] }
diff --git a/src/cal/day15.rs b/src/cal/day15.rs
new file mode 100644
index 0000000..049a165
--- /dev/null
+++ b/src/cal/day15.rs
@@ -0,0 +1,117 @@
+use axum::{http::StatusCode, response::IntoResponse, routing::post, Json, Router};
+
+pub(crate) fn router() -> Router {
+    Router::new()
+        .route("/15/nice", post(nice))
+        .route("/15/game", post(game))
+}
+
+#[derive(serde::Deserialize)]
+struct Nice {
+    input: String,
+}
+
+async fn nice(Json(Nice { input }): Json<Nice>) -> impl IntoResponse {
+    let vowels = input
+        .chars()
+        .filter(|&c| c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u' || c == 'y')
+        .count();
+    let repeat = input
+        .as_bytes()
+        .windows(2)
+        .any(|c| c[0].is_ascii_alphabetic() && c[0] == c[1]);
+    let substrs = input.contains("ab")
+        || input.contains("cd")
+        || input.contains("pq")
+        || input.contains("xy");
+    if vowels > 2 && repeat && !substrs {
+        (StatusCode::OK, "{\"result\":\"nice\"}".to_string())
+    } else {
+        (
+            StatusCode::BAD_REQUEST,
+            "{\"result\":\"naughty\"}".to_string(),
+        )
+    }
+}
+
+#[derive(serde::Serialize)]
+struct Game {
+    result: String,
+    reason: String,
+}
+
+async fn game(Json(Nice { input }): Json<Nice>) -> (StatusCode, Json<Game>) {
+    let code;
+    let result;
+    let reason;
+    let r1 = input.len() >= 8;
+    let r2 = input.chars().any(|c| c.is_ascii_uppercase())
+        && input.chars().any(|c| c.is_ascii_lowercase())
+        && input.chars().any(|c| c.is_ascii_digit());
+    let r3 = input.chars().filter(char::is_ascii_digit).count() >= 5;
+    let r4 = regex::Regex::new(r"\d+")
+        .expect("Regex should be valid")
+        .captures_iter(&input)
+        .map(|c| c.extract::<0>().0)
+        .map(|s| s.parse::<i32>().expect("All matches are only digits"))
+        .sum::<i32>()
+        == 2023;
+    let r5 = regex::Regex::new(r".*j.*o.*y.*")
+        .expect("Regex should be valid")
+        .is_match(&input)
+        && input.chars().filter(|&c| c == 'j').count() == 1
+        && input.chars().filter(|&c| c == 'o').count() == 1
+        && input.chars().filter(|&c| c == 'y').count() == 1;
+    let r6 = input.as_bytes().windows(3).any(|c| {
+        c[0] != c[1] && c[0] == c[2] && c[0].is_ascii_alphabetic() && c[1].is_ascii_alphabetic()
+    });
+    let r7 = input
+        .chars()
+        .any(|c| ('\u{2980}'..='\u{2BFF}').contains(&c));
+    let r8 = regex::Regex::new(r"[\p{Emoji}--\p{Ascii}]")
+        .expect("Regex should be valid")
+        .is_match(&input);
+    let r9 = sha256::digest(input.clone()).ends_with('a');
+    if !r1 {
+        code = StatusCode::BAD_REQUEST;
+        result = "naughty".to_string();
+        reason = "8 chars".to_string();
+    } else if !r2 {
+        code = StatusCode::BAD_REQUEST;
+        result = "naughty".to_string();
+        reason = "more types of chars".to_string();
+    } else if !r3 {
+        code = StatusCode::BAD_REQUEST;
+        result = "naughty".to_string();
+        reason = "55555".to_string();
+    } else if !r4 {
+        code = StatusCode::BAD_REQUEST;
+        result = "naughty".to_string();
+        reason = "math is hard".to_string();
+    } else if !r5 {
+        code = StatusCode::NOT_ACCEPTABLE;
+        result = "naughty".to_string();
+        reason = "not joyful enough".to_string();
+    } else if !r6 {
+        code = StatusCode::UNAVAILABLE_FOR_LEGAL_REASONS;
+        result = "naughty".to_string();
+        reason = "illegal: no sandwich".to_string();
+    } else if !r7 {
+        code = StatusCode::RANGE_NOT_SATISFIABLE;
+        result = "naughty".to_string();
+        reason = "outranged".to_string();
+    } else if !r8 {
+        code = StatusCode::UPGRADE_REQUIRED;
+        result = "naughty".to_string();
+        reason = "😳".to_string();
+    } else if !r9 {
+        code = StatusCode::IM_A_TEAPOT;
+        result = "naughty".to_string();
+        reason = "not a coffee brewer".to_string();
+    } else {
+        code = StatusCode::OK;
+        result = "nice".to_string();
+        reason = "that's a nice password".to_string();
+    }
+    (code, Json(Game { result, reason }))
+}
diff --git a/src/cal/mod.rs b/src/cal/mod.rs
index 8edecbe..469e2b4 100644
--- a/src/cal/mod.rs
+++ b/src/cal/mod.rs
@@ -8,6 +8,7 @@ mod day11;
 mod day12;
 mod day13;
 mod day14;
+mod day15;
 
 pub(crate) fn router(pool: sqlx::PgPool) -> axum::Router {
     axum::Router::new()
@@ -21,4 +22,5 @@ pub(crate) fn router(pool: sqlx::PgPool) -> axum::Router {
         .nest("/", day12::router())
         .nest("/", day13::router(pool))
         .nest("/", day14::router())
+        .nest("/", day15::router())
 }