diff --git a/Cargo.lock b/Cargo.lock
index 8d6b88d..ec79b71 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -89,7 +89,7 @@ checksum = "a27b8a3a6e1a44fa4c8baf1f653e4172e81486d4941f2237e20dc2d0cf4ddff1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -359,7 +359,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "strsim",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -370,7 +370,7 @@ checksum = "d336a2a514f6ccccaa3e09b02d41d35330c07ddf03a62165fcec10bb561c7806"
 dependencies = [
  "darling_core",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -391,7 +391,7 @@ dependencies = [
  "darling",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -401,7 +401,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4abae7035bf79b9877b779505d8cf3749285b80c43941eda66604841889451dc"
 dependencies = [
  "derive_builder_core",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -537,6 +537,12 @@ dependencies = [
  "log",
 ]
 
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
 [[package]]
 name = "errno"
 version = "0.3.9"
@@ -669,6 +675,12 @@ dependencies = [
  "crunchy",
 ]
 
+[[package]]
+name = "hashbrown"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
+
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -791,6 +803,17 @@ dependencies = [
  "unicode-normalization",
 ]
 
+[[package]]
+name = "indexmap"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68b900aa2f7301e21c36462b170ee99994de34dff39a4a6a528e80e7376d07e5"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+ "serde",
+]
+
 [[package]]
 name = "indicatif"
 version = "0.17.8"
@@ -1281,7 +1304,7 @@ checksum = "a7ce64b975ed4f123575d11afd9491f2e37bbd5813fbfbc0f09ae1fbddea74e0"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -1478,7 +1501,7 @@ dependencies = [
  "phf_shared",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -1507,7 +1530,7 @@ checksum = "2f38a4412a78282e09a2cf38d195ea5420d15ba0602cb375210efbc877243965"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -1552,6 +1575,30 @@ dependencies = [
  "zerocopy",
 ]
 
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.86"
@@ -1609,7 +1656,7 @@ dependencies = [
  "proc-macro2",
  "pyo3-macros-backend",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -1622,7 +1669,7 @@ dependencies = [
  "proc-macro2",
  "pyo3-build-config",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -1829,6 +1876,7 @@ dependencies = [
  "sbv2_core",
  "serde",
  "tokio",
+ "utoipa",
 ]
 
 [[package]]
@@ -1886,7 +1934,7 @@ checksum = "243902eda00fad750862fc144cea25caca5e20d615af0a81bee94ca738f1df1f"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -2025,7 +2073,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "rustversion",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -2034,6 +2082,16 @@ version = "2.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
 
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "unicode-ident",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.77"
@@ -2091,7 +2149,7 @@ checksum = "08904e7672f5eb876eaaf87e0ce17857500934f4981c4a0ab2b4aa98baac7fc3"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -2167,7 +2225,7 @@ checksum = "693d596312e88961bc67d7f1f97af8a70227d9f90c31bba5806eec004978d752"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
@@ -2332,6 +2390,31 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "utoipa"
+version = "4.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5afb1a60e207dca502682537fefcfd9921e71d0b83e9576060f09abc6efab23"
+dependencies = [
+ "indexmap",
+ "serde",
+ "serde_json",
+ "utoipa-gen",
+]
+
+[[package]]
+name = "utoipa-gen"
+version = "4.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7bf0e16c02bc4bf5322ab65f10ab1149bdbcaa782cba66dc7057370a3f8190be"
+dependencies = [
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "regex",
+ "syn 2.0.77",
+]
+
 [[package]]
 name = "version_check"
 version = "0.9.5"
@@ -2492,7 +2575,7 @@ checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.77",
 ]
 
 [[package]]
diff --git a/sbv2_api/Cargo.toml b/sbv2_api/Cargo.toml
index a49e149..01b4a3a 100644
--- a/sbv2_api/Cargo.toml
+++ b/sbv2_api/Cargo.toml
@@ -12,6 +12,7 @@ log = "0.4.22"
 sbv2_core = { version = "0.2.0-alpha", path = "../sbv2_core" }
 serde = { version = "1.0.210", features = ["derive"] }
 tokio = { version = "1.40.0", features = ["full"] }
+utoipa = { version = "4.2.3", features = ["axum_extras"] }
 
 [features]
 coreml = ["sbv2_core/coreml"]
@@ -19,4 +20,4 @@ cuda = ["sbv2_core/cuda"]
 cuda_tf32 = ["sbv2_core/cuda_tf32"]
 dynamic = ["sbv2_core/dynamic"]
 directml = ["sbv2_core/directml"]
-tensorrt = ["sbv2_core/tensorrt"]
\ No newline at end of file
+tensorrt = ["sbv2_core/tensorrt"]
diff --git a/sbv2_api/src/main.rs b/sbv2_api/src/main.rs
index 5a82a1e..e94a625 100644
--- a/sbv2_api/src/main.rs
+++ b/sbv2_api/src/main.rs
@@ -11,10 +11,36 @@ use std::env;
 use std::sync::Arc;
 use tokio::fs;
 use tokio::sync::Mutex;
+use utoipa::{OpenApi, ToSchema};
 
 mod error;
 use crate::error::AppResult;
 
+#[derive(OpenApi)]
+#[openapi(
+    paths(openapi, models, synthesize),
+    components(schemas(SynthesizeRequest))
+)]
+struct ApiDoc;
+
+#[utoipa::path(
+    get,
+    path = "/docs/openapi.json",
+    responses(
+        (status = 200, description = "JSON file", body = ())
+    )
+)]
+async fn openapi() -> Json<utoipa::openapi::OpenApi> {
+    Json(ApiDoc::openapi())
+}
+
+#[utoipa::path(
+    get,
+    path = "/models",
+    responses(
+        (status = 200, description = "Return model list", body = Vec<String>),
+    )
+)]
 async fn models(State(state): State<AppState>) -> AppResult<impl IntoResponse> {
     Ok(Json(state.tts_model.lock().await.models()))
 }
@@ -27,7 +53,7 @@ fn length_default() -> f32 {
     1.0
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, ToSchema)]
 struct SynthesizeRequest {
     text: String,
     ident: String,
@@ -37,6 +63,14 @@ struct SynthesizeRequest {
     length_scale: f32,
 }
 
+#[utoipa::path(
+    post,
+    path = "/synthesize",
+    request_body = SynthesizeRequest,
+    responses(
+        (status = 200, description = "Return audio/wav", body = Vec<u8>)
+    )
+)]
 async fn synthesize(
     State(state): State<AppState>,
     Json(SynthesizeRequest {