diff --git a/tower-http/src/services/fs/serve_dir/mod.rs b/tower-http/src/services/fs/serve_dir/mod.rs
index 61b956d1..122907e7 100644
--- a/tower-http/src/services/fs/serve_dir/mod.rs
+++ b/tower-http/src/services/fs/serve_dir/mod.rs
@@ -76,6 +76,7 @@ impl ServeDir<DefaultServeDirFallback> {
             precompressed_variants: None,
             variant: ServeVariant::Directory {
                 append_index_html_on_directories: true,
+                html_as_default_extension: true,
             },
             fallback: None,
             call_fallback_on_method_not_allowed: false,
@@ -105,9 +106,7 @@ impl<F> ServeDir<F> {
     /// Defaults to `true`.
     pub fn append_index_html_on_directories(mut self, append: bool) -> Self {
         match &mut self.variant {
-            ServeVariant::Directory {
-                append_index_html_on_directories,
-            } => {
+            ServeVariant::Directory { append_index_html_on_directories, .. } => {
                 *append_index_html_on_directories = append;
                 self
             }
@@ -115,6 +114,19 @@ impl<F> ServeDir<F> {
         }
     }
 
+    /// If the requested path doesn't specify a file extension, append `.html`.
+    ///
+    /// Defaults to `true`.
+    pub fn html_as_default_extension(mut self, append: bool) -> Self {
+        match &mut self.variant {
+            ServeVariant::Directory { html_as_default_extension, .. } => {
+                *html_as_default_extension = append;
+                self
+            }
+            ServeVariant::SingleFile { mime: _ } => self,
+        }
+    }
+
     /// Set a specific read buffer chunk size.
     ///
     /// The default capacity is 64kb.
@@ -443,6 +455,7 @@ opaque_future! {
 enum ServeVariant {
     Directory {
         append_index_html_on_directories: bool,
+        html_as_default_extension: bool,
     },
     SingleFile {
         mime: HeaderValue,
@@ -454,6 +467,7 @@ impl ServeVariant {
         match self {
             ServeVariant::Directory {
                 append_index_html_on_directories: _,
+                html_as_default_extension: _,
             } => {
                 let path = requested_path.trim_start_matches('/');
 
diff --git a/tower-http/src/services/fs/serve_dir/open_file.rs b/tower-http/src/services/fs/serve_dir/open_file.rs
index f182d422..d92493c1 100644
--- a/tower-http/src/services/fs/serve_dir/open_file.rs
+++ b/tower-http/src/services/fs/serve_dir/open_file.rs
@@ -59,6 +59,7 @@ pub(super) async fn open_file(
     let mime = match variant {
         ServeVariant::Directory {
             append_index_html_on_directories,
+            html_as_default_extension,
         } => {
             // Might already at this point know a redirect or not found result should be
             // returned which corresponds to a Some(output). Otherwise the path might be
@@ -67,6 +68,7 @@ pub(super) async fn open_file(
                 &mut path_to_file,
                 req.uri(),
                 append_index_html_on_directories,
+                html_as_default_extension,
             )
             .await
             {
@@ -254,18 +256,23 @@ async fn maybe_redirect_or_append_path(
     path_to_file: &mut PathBuf,
     uri: &Uri,
     append_index_html_on_directories: bool,
+    html_as_default_extension: bool,
 ) -> Option<OpenFileOutput> {
-    if !is_dir(path_to_file).await {
+    if is_dir(path_to_file).await == Some(false) {
         return None;
     }
 
-    if !append_index_html_on_directories {
+    if !append_index_html_on_directories && !html_as_default_extension {
         return Some(OpenFileOutput::FileNotFound);
     }
 
-    if uri.path().ends_with('/') {
+    let path = uri.path();
+    if append_index_html_on_directories && path.ends_with('/') {
         path_to_file.push("index.html");
         None
+    } else if html_as_default_extension && path_to_file.extension().is_none() {
+        path_to_file.set_extension("html");
+        None
     } else {
         let location =
             HeaderValue::from_str(&append_slash_on_path(uri.clone()).to_string()).unwrap();
@@ -283,10 +290,11 @@ fn try_parse_range(
     })
 }
 
-async fn is_dir(path_to_file: &Path) -> bool {
+async fn is_dir(path_to_file: &Path) -> Option<bool> {
     tokio::fs::metadata(path_to_file)
         .await
-        .map_or(false, |meta_data| meta_data.is_dir())
+        .ok()
+        .map(|meta_data| meta_data.is_dir())
 }
 
 fn append_slash_on_path(uri: Uri) -> Uri {