diff --git a/app.py b/app.py
index e319c05..62059e7 100755
--- a/app.py
+++ b/app.py
@@ -53,6 +53,7 @@ if useSSL:
 if debug:
     print(HTTP_url_scheme)
 
+upload_candidates = {}
 
 @auth.verify_password
 def verify_password(username, password):
@@ -159,7 +160,12 @@ def list_media_files(folder):
         for fd in files:
             if len(fd.split('.')) > 1:
                 if fd.split('.')[1] in media_exts:
-                    medias.append(fd)
+                    # TODO : Return a dict list [{"filename":"foo", "size":-1}, {...}]
+                    fd_size = os.stat(folder + fd).st_size
+                    file_dict = {"filename": fd, "size": fd_size}
+                    if debug:
+                        print(str(file_dict))
+                    medias.append(file_dict)
         return medias
     else:
         return []
@@ -212,9 +218,34 @@ def shutdown():
 @app.route('/upload', methods=['GET', 'POST'])
 @auth.login_required
 def upload_file(over_write=1):
+    global upload_candidates
+    media_files = list_media_files(upload_folder)
     if debug:
         print("Existing files : {}".format(str(list_media_files(upload_folder))))
+    if request.method == "GET":
+        # Send candidates list
+        if debug:
+            print("GET :" + str(upload_candidates))
+        return upload_candidates
     if request.method == "POST":
+        if request.get_json():
+            # JSON received, parse it
+            upload_candidates = request.get_json()
+            # ~ upload_candidates = [candidate for candidate in upload_candidates if candidate not in media_files]
+            upload_laureates = []
+            for candidate in upload_candidates:
+                if candidate not in media_files:
+                    upload_laureates.append(candidate)
+                # TODO : Compare existing file size to new file and upload if different
+                # received data of type list of dict [{"filename": "foo", "size": 0}, {...}]
+                elif candidate in media_files:
+                    duplicate_index = media_files.index(candidate) 
+                    if candidate["size"] != media_files[duplicate_index]["size"]:
+                        upload_laureates.append(candidate)
+            upload_candidates = upload_laureates
+            if debug:
+                print("POST :" + str(upload_candidates))
+            return upload_candidates
         # Check if the post request has the file part
         if "file" not in request.files:
             return _("No file part: {}").format(str(request.files))
@@ -226,7 +257,7 @@ def upload_file(over_write=1):
         if file and allowed_ext(file.filename):
             if debug:
                 print("Uploading file {} in {}.".format(str(file.filename.strip("/")), upload_folder))
-            if (file.filename.strip("/") not in list_media_files(upload_folder)) and over_write:
+            if (file.filename.strip("/") not in media_files) or over_write:
                 filename = secure_filename(file.filename)
                 file.save(os.path.join(upload_folder, filename))
                 return _("File saved in {}").format(upload_folder)
@@ -237,7 +268,6 @@ def upload_file(over_write=1):
 
 
 @app.route("/thumb/<media>")
-@auth.login_required
 def get_thumbnail(media):
     if media:
         media_full_path = thumbnails_folder + os.sep + media + ".jpg"