diff --git a/package-lock.json b/package-lock.json
index 4cf810c..65ad597 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5,6 +5,7 @@
   "packages": {
     "": {
       "dependencies": {
+        "ace-builds": "^1.43.3",
         "bootstrap": "^5.3.8"
       }
     },
@@ -18,6 +19,11 @@
         "url": "https://opencollective.com/popperjs"
       }
     },
+    "node_modules/ace-builds": {
+      "version": "1.43.3",
+      "resolved": "https://registry.npmjs.org/ace-builds/-/ace-builds-1.43.3.tgz",
+      "integrity": "sha512-MCl9rALmXwIty/4Qboijo/yNysx1r6hBTzG+6n/TiOm5LFhZpEvEIcIITPFiEOEFDfgBOEmxu+a4f54LEFM6Sg=="
+    },
     "node_modules/bootstrap": {
       "version": "5.3.8",
       "resolved": "https://registry.npmjs.org/bootstrap/-/bootstrap-5.3.8.tgz",
diff --git a/package.json b/package.json
index 719e5df..5374149 100644
--- a/package.json
+++ b/package.json
@@ -1,5 +1,6 @@
 {
   "dependencies": {
+    "ace-builds": "^1.43.3",
     "bootstrap": "^5.3.8"
   }
 }
diff --git a/src/cmd/collerd/README.md b/src/cmd/collerd/README.md
index b85139a..231c887 100644
--- a/src/cmd/collerd/README.md
+++ b/src/cmd/collerd/README.md
@@ -31,11 +31,12 @@ The file format is **JSON**:
 * **prometheus_route** (string): Route to expose Prometheus metrics (default "/metrics")
 * **prometheus_notes_metric** (string): Name of the notes count metric (default "collerd_notes")
 * **observation_internal** (int): Number of seconds to wait between two observations (default 60)
-* **languages** ([]string): List of supported [languages](https://github.com/microsoft/monaco-editor/tree/main/src/basic-languages)
+* **languages** ([]string): List of supported [languages](https://github.com/ajaxorg/ace/tree/master/src/mode)
 * **language** (string): Default language (default "text")
 * **enable_upload_file_button** (bool): Display the upload file button in the UI (default true)
 * **tls_cert_file** (string): Path to TLS certificate file to enable HTTPS
 * **tls_key_file** (string): Path to TLS key file to enable HTTPS
+* **ace_directory** (string): Serve [Ace](hhttps://ace.c9.io/) assets from this local directory (ex: "./node_modules/ace-builds"). See **Dependencies** for details.
 * **bootstrap_directory** (string): Serve [Bootstrap](https://getbootstrap.com/) assets from this local directory (ex: "./node_modules/bootstrap/dist"). See **Dependencies** for details.
 
 The configuration file is not required but the service might not be exposed to the public.
@@ -85,12 +86,12 @@ Errors return **500 Server Internal Error** with the **JSON** payload:
 
 The web interface depends on:
 
+- [Ace](https://ace.c9.io/)
 - [Bootstrap](https://getbootstrap.com/)
-- [Monaco Editor](https://github.com/microsoft/monaco-editor/)
 
 By default, those dependencies are fetched from **remote CDN** services by the client.
 
-If you would like to download them to serve them locally:
+If you would like to download and serve them locally:
 
 ```
 npm install
@@ -106,8 +107,7 @@ Then configure the local directories:
 
 ```json
 {
+  "ace_directory": "./node_modules/ace-builds",
   "bootstrap_directory": "./node_modules/bootstrap/dist"
 }
-```
-
-Downloading Monaco Editor is not supported yet.
+```
\ No newline at end of file
diff --git a/src/server/config.go b/src/server/config.go
index 97983f9..7a6830e 100644
--- a/src/server/config.go
+++ b/src/server/config.go
@@ -28,6 +28,7 @@ type Config struct {
 	EnableUploadFileButton bool     `json:"enable_upload_file_button"`
 	TLSCertFile            string   `json:"tls_cert_file"`
 	TLSKeyFile             string   `json:"tls_key_file"`
+	AceDirectory           string   `json:"ace_directory"`
 	BootstrapDirectory     string   `json:"bootstrap_directory"`
 }
 
@@ -56,22 +57,21 @@ func NewConfig() *Config {
 		PrometheusNotesMetric: "collerd_notes",
 		ObservationInterval:   60,
 		Languages: []string{
-			"Text",
-			"CSS",
-			"Dockerfile",
-			"Go",
-			"HCL",
-			"HTML",
-			"Javascript",
-			"JSON",
-			"Markdown",
-			"Perl",
-			"Python",
-			"Ruby",
-			"Rust",
-			"Shell",
-			"SQL",
-			"YAML",
+			"css",
+			"dockerfile",
+			"golang",
+			"html",
+			"javascript",
+			"json",
+			"markdown",
+			"perl",
+			"python",
+			"ruby",
+			"rust",
+			"sh",
+			"sql",
+			"text",
+			"yaml",
 		},
 		Language:               "text",
 		EnableUploadFileButton: true,
diff --git a/src/server/handlers_web.go b/src/server/handlers_web.go
index d059d7a..caebf9d 100644
--- a/src/server/handlers_web.go
+++ b/src/server/handlers_web.go
@@ -21,11 +21,13 @@ type PageData struct {
 	Version                string
 	Expirations            []int
 	Expiration             int
+	Language               string
 	Languages              []string
 	Err                    error
 	URL                    string
 	Note                   *Note
 	EnableUploadFileButton bool
+	AceDirectory           string
 	BootstrapDirectory     string
 }
 
diff --git a/src/server/server.go b/src/server/server.go
index f64e2cc..6e670fc 100644
--- a/src/server/server.go
+++ b/src/server/server.go
@@ -113,7 +113,9 @@ func (s *Server) Start() error {
 		Title:              s.config.Title,
 		Expirations:        s.config.Expirations,
 		Expiration:         s.config.Expiration,
+		Language:           s.config.Language,
 		Languages:          s.config.Languages,
+		AceDirectory:       s.config.AceDirectory,
 		BootstrapDirectory: s.config.BootstrapDirectory,
 	}
 
@@ -159,6 +161,10 @@ func (s *Server) Start() error {
 	}
 	r.Path("/{id:[a-zA-Z0-9]+}.html").Handler(webNoteHandler).Methods("GET")
 
+	if s.config.AceDirectory != "" {
+		r.PathPrefix("/static/ace-builds/").Handler(http.StripPrefix("/static/ace-builds/", http.FileServer(http.Dir(s.config.AceDirectory))))
+	}
+
 	if s.config.BootstrapDirectory != "" {
 		r.PathPrefix("/static/bootstrap/").Handler(http.StripPrefix("/static/bootstrap/", http.FileServer(http.Dir(s.config.BootstrapDirectory))))
 	}
@@ -168,10 +174,10 @@ func (s *Server) Start() error {
 	addr := fmt.Sprintf("%s:%d", s.config.ListenAddress, s.config.ListenPort)
 
 	if s.config.HasTLS() {
-		s.logger.Info(fmt.Sprintf("listening to %s:%d (https)", s.config.ListenAddress, s.config.ListenPort))
+		s.logger.Info(fmt.Sprintf("listening to %s:%d", s.config.ListenAddress, s.config.ListenPort), slog.Any("scheme", "http"))
 		return http.ListenAndServeTLS(addr, s.config.TLSCertFile, s.config.TLSKeyFile, r)
 	} else {
-		s.logger.Info(fmt.Sprintf("listening to %s:%d (http)", s.config.ListenAddress, s.config.ListenPort))
+		s.logger.Info(fmt.Sprintf("listening to %s:%d", s.config.ListenAddress, s.config.ListenPort), slog.Any("scheme", "https"))
 		return http.ListenAndServe(addr, r)
 	}
 }
diff --git a/src/server/templates/index.html b/src/server/templates/index.html
index 4c18a78..fd034fd 100644
--- a/src/server/templates/index.html
+++ b/src/server/templates/index.html
@@ -40,15 +40,17 @@
                     <select class="form-select" aria-label="Expiration" id="expiration" name="expiration">
                         <option disabled>Expiration</option>
                         {{range $exp := .Expirations}}
-                        <option {{ if eq $exp $.Expiration }}selected="selected"{{end}} value="{{$exp}}">{{HumanDuration $exp}}</option>
+                        <option {{ if eq $exp $.Expiration }}selected="selected" {{end}} value="{{$exp}}">
+                            {{HumanDuration $exp}}</option>
                         {{end}}
                     </select>
                 </div>
                 <div class="col">
                     <select class="form-select" aria-label="Language" id="language" name="language">
-                        <option selected="selected" value="" disabled>Language</option>
-                        {{range .Languages}}
-                        <option value="{{lower .}}">{{.}}</option>
+                        <option disabled>Language</option>
+                        {{range $language := .Languages}}
+                        <option {{ if eq $language $.Language }}selected="selected" {{end}}value="{{lower .}}">
+                            {{$language}}</option>
                         {{end}}
                     </select>
                 </div>
@@ -69,36 +71,36 @@
                 </div>
             </div>
         </div>
-        <script src="https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.52.2/min/vs/loader.min.js"></script>
+        <script
+            src="{{if .AceDirectory}}/static/ace-builds{{else}}https://cdn.jsdelivr.net/npm/ace-builds@1.43.3{{end}}/src-noconflict/ace.js"
+            type="text/javascript" charset="utf-8"></script>
         <script>
-            require.config({ paths: { vs: 'https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.52.2/min/vs' } });
+            var editor = ace.edit("editor");
+            if (document.documentElement.getAttribute('data-bs-theme') == 'light') {
+                editor.setTheme("ace/theme/github_light_default");
+            } else {
+                editor.setTheme("ace/theme/github_dark");
+            }
 
-            require(['vs/editor/editor.main'], function () {
-                var editor = monaco.editor.create(document.getElementById('editor'), {
-                    theme: document.documentElement.getAttribute('data-bs-theme') == 'light' ? "vs" : "vs-dark",
-                    language: document.getElementById("language").value,
-                });
+            // Syntax highlighting
+            document.getElementById("language").addEventListener("change", (e) => {
+                if (e.target.value != "") {
+                    editor.getSession().setMode("ace/mode/" + e.target.value);
+                }
+            });
 
-                // Syntax highlighting
-                document.getElementById("language").addEventListener("change", (e) => {
-                    if (e.target.value != "") {
-                        monaco.editor.setModelLanguage(editor.getModel(), e.target.value);
-                    }
-                });
+            // Dark mode
+            document.getElementById("lightSwitch").addEventListener("click", () => {
+                if (document.documentElement.getAttribute('data-bs-theme') == 'light') {
+                    editor.setTheme("ace/theme/github_light_default")
+                } else if (document.documentElement.getAttribute('data-bs-theme') == 'dark') {
+                    editor.setTheme("ace/theme/github_dark")
+                }
+            });
 
-                // Dark mode
-                document.getElementById("lightSwitch").addEventListener("click", () => {
-                    if (document.documentElement.getAttribute('data-bs-theme') == 'light') {
-                        monaco.editor.setTheme("vs")
-                    } else if (document.documentElement.getAttribute('data-bs-theme') == 'dark') {
-                        monaco.editor.setTheme("vs-dark")
-                    }
-                });
-
-                // Copy content on submit
-                document.getElementById("form").addEventListener("formdata", (e) => {
-                    e.formData.append('content', editor.getModel().getValue());
-                });
+            // Copy content on submit
+            document.getElementById("form").addEventListener("formdata", (e) => {
+                e.formData.append('content', editor.getValue());
             });
         </script>
     </form>
diff --git a/src/server/templates/note.html b/src/server/templates/note.html
index 2570851..ad36db7 100644
--- a/src/server/templates/note.html
+++ b/src/server/templates/note.html
@@ -32,27 +32,31 @@
             <div id="editor" name="editor" class="form-control"
                 style="height: 300px; resize: vertical; overflow: auto;"></div>
         </div>
-        <script src="https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.52.2/min/vs/loader.min.js"></script>
+        <script
+            src="{{if .AceDirectory}}/static/ace-builds{{else}}https://cdn.jsdelivr.net/npm/ace-builds@1.43.3{{end}}/src-noconflict/ace.js"
+            type="text/javascript" charset="utf-8"></script>
         <script>
-            require.config({ paths: { vs: 'https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.52.2/min/vs' } });
+            var editor = ace.edit("editor");
+            editor.setValue("{{string .Note.Content}}");
+            editor.setReadOnly(true);
+            editor.getSession().setMode("ace/mode/{{.Note.Language}}");
+            editor.getSession().selection.clearSelection();
 
-            require(['vs/editor/editor.main'], function () {
-                var editor = monaco.editor.create(document.getElementById('editor'), {
-                    theme: document.documentElement.getAttribute('data-bs-theme') == 'light' ? "vs" : "vs-dark",
-                    language: "{{.Note.Language}}",
-                    readOnly: true,
-                    value: "{{string .Note.Content}}"
-                });
+            if (document.documentElement.getAttribute('data-bs-theme') == 'light') {
+                editor.setTheme("ace/theme/github_light_default");
+            } else {
+                editor.setTheme("ace/theme/github_dark");
+            }
 
-                // Dark mode
-                document.getElementById("lightSwitch").addEventListener("click", () => {
-                    if (document.documentElement.getAttribute('data-bs-theme') == 'light') {
-                        monaco.editor.setTheme("vs")
-                    } else if (document.documentElement.getAttribute('data-bs-theme') == 'dark') {
-                        monaco.editor.setTheme("vs-dark")
-                    }
-                });
+            // Dark mode
+            document.getElementById("lightSwitch").addEventListener("click", () => {
+                if (document.documentElement.getAttribute('data-bs-theme') == 'light') {
+                    editor.setTheme("ace/theme/github_light_default")
+                } else if (document.documentElement.getAttribute('data-bs-theme') == 'dark') {
+                    editor.setTheme("ace/theme/github_dark")
+                }
             });
+
         </script>
     </div>
     {{end}}