diff --git a/waifu2x/unlimited_waifu2x/appendix/unlimited.waifu2x.net b/waifu2x/unlimited_waifu2x/appendix/unlimited.waifu2x.net
index 7429494b..4dae7691 100644
--- a/waifu2x/unlimited_waifu2x/appendix/unlimited.waifu2x.net
+++ b/waifu2x/unlimited_waifu2x/appendix/unlimited.waifu2x.net
@@ -8,9 +8,19 @@ server {
        }
        location / {
            add_header Cache-Control "public, max-age=3600, must-revalidate";
+           # If you want to enable multi-threading
+           #add_header Cross-Origin-Resource-Policy "cross-origin";
+           #add_header Cross-Origin-Embedder-Policy "require-corp";
+           #add_header Cross-Origin-Opener-Policy "same-origin";
        }
        location ~* \.(onnx|pth) {
            add_header Cache-Control "public, max-age=86400, must-revalidate";
        }
+       location ~* \.wasm$ {
+           types {
+               application/wasm wasm;
+           }
+       }
+
        listen 80;
 }
diff --git a/waifu2x/unlimited_waifu2x/public_html/script.js b/waifu2x/unlimited_waifu2x/public_html/script.js
index 1d8cbf6a..c57c3bb3 100644
--- a/waifu2x/unlimited_waifu2x/public_html/script.js
+++ b/waifu2x/unlimited_waifu2x/public_html/script.js
@@ -542,6 +542,7 @@ const onnx_runner = {
 $(function () {
     /* init */
     ort.env.wasm.proxy = true;
+    ort.env.wasm.numThreads = navigator.hardwareConcurrency;
 
     function removeAlpha(blob)
     {
diff --git a/waifu2x/unlimited_waifu2x/test_server.py b/waifu2x/unlimited_waifu2x/test_server.py
index a8a66bcb..871f9343 100644
--- a/waifu2x/unlimited_waifu2x/test_server.py
+++ b/waifu2x/unlimited_waifu2x/test_server.py
@@ -2,9 +2,15 @@
 # View at http://localhost:8812/
 # Do not use this server in product environments.
 import bottle
+import argparse
 from os import path
 
 
+parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+parser.add_argument("--cors", action="store_true",
+                    help=("Add CORS header for testing wasm multi-threading."
+                          " google-chrome does not work for security reasons (localhost CORS), use firefox"))
+args = parser.parse_args()
 ROOT_DIR = path.abspath(path.join(path.dirname(__file__), "public_html"))
 
 
@@ -12,7 +18,12 @@
 def static_file(url):
     if not url:
         url = "index.html"
-    return bottle.static_file(url, root=ROOT_DIR)
+    response = bottle.static_file(url, root=ROOT_DIR)
+    if args.cors:
+        response.set_header("Cross-Origin-Resource-Policy", "cross-origin")
+        response.set_header("Cross-Origin-Embedder-Policy", "require-corp")
+        response.set_header("Cross-Origin-Opener-Policy", "same-origin")
+    return response
 
 
 def main():