diff --git a/demo/www/index.html b/demo/www/index.html
index 017e877..3ef797c 100644
--- a/demo/www/index.html
+++ b/demo/www/index.html
@@ -42,6 +42,7 @@
               <a class="dropdown-item" id="random-option">Random Generator</a>
             </div>
           </li>
+          <input class="form-control mr-sm-2" id="seed" type="search" placeholder="Seed" aria-label="Seed">
         </ul>
       </div>
     </nav>
diff --git a/demo/www/index.js b/demo/www/index.js
index 61fe903..79afca5 100644
--- a/demo/www/index.js
+++ b/demo/www/index.js
@@ -19,34 +19,41 @@ canvas.width = (CELL_SIZE + 1) * width + 1;
 
 const ctx = canvas.getContext('2d');
 
+function get_seed() {
+    var seed_text = document.getElementById("seed").value;
+    if( seed_text.length > 0) {
+        return Number(seed_text);
+    } 
+    return Date.now();
+}
+
 // Map generators
 function newCellularAutomata() {
-    var seed = Date.now();
-    world = World.new_cellular_automata(width, height, seed);
+    world = World.new_cellular_automata(width, height, get_seed());
     requestAnimationFrame(renderLoop);
 }
 
 function newSimpleRooms() {
     var seed = Date.now();
-    world = World.new_simple_rooms(width, height, seed);
+    world = World.new_simple_rooms(width, height, get_seed());
     requestAnimationFrame(renderLoop);
 }
 
 function newBspInterior() {
     var seed = Date.now();
-    world = World.new_bsp_interior(width, height, seed);
+    world = World.new_bsp_interior(width, height, get_seed());
     requestAnimationFrame(renderLoop);
 }
 
 function newDrunkard() {
     var seed = Date.now();
-    world = World.new_drunkard(width, height, seed);
+    world = World.new_drunkard(width, height, get_seed());
     requestAnimationFrame(renderLoop);
 }
 
 function newRandomGen() {
     var seed = Date.now();
-    world = World.new_random(width, height, seed);
+    world = World.new_random(width, height, get_seed());
     requestAnimationFrame(renderLoop);
 }