diff --git a/app.py b/app.py
index f03448026..1cd12d1bb 100644
--- a/app.py
+++ b/app.py
@@ -1,7 +1,129 @@
-from flask import Flask, render_template
+from flask import Flask, request, send_file, render_template_string
+import pandas as pd
+from io import BytesIO
 
 app = Flask(__name__)
 
-@app.route("/")
-def hello_world():
-    return render_template("index.html", title="Hello")
+# ---------------- SORT ORDER ---------------- #
+
+SHAPE_ORDER = [
+    "ROUND","ROU.MOD.","OVAL","OV.MOD.","STEP OVAL",
+    "PEAR","PE.MOD.","STEP PEAR",
+    "MARQUISE","MQ.MOD","STEP MARQUISE",
+    "PRINCESS","RAD","SQ.RAD",
+    "EMERALD","ASSCHER","SQ.CUS.","SQ.CUS.MOD.","LO.CUS.",
+    "HEXAGON","HEART"
+]
+
+SIZE_ORDER = [
+    "10.000-10.999","9.000-9.999","8.000-8.999","7.000-7.999",
+    "6.000-6.999","5.500-5.999","5.000-5.499","4.500-4.749",
+    "4.250-4.499","4.000-4.249","3.750-3.999","3.500-3.749",
+    "3.250-3.499","3.000-3.249","2.750-2.999","2.500-2.749",
+    "2.250-2.499","2.000-2.249","1.900-1.999","1.800-1.899",
+    "1.700-1.799","1.600-1.699","1.500-1.599","1.400-1.499",
+    "1.300-1.399","1.200-1.299","1.100-1.199","1.000-1.099",
+    "0.960-0.999","0.900-0.959","0.700-0.799","0.500-0.599","0.400-0.459"
+]
+
+CLARITY_ORDER = ["FL","IF","VVS1","VVS2","VS1","VS2","SI1","SI2","SI3","PRE","STD"]
+
+DZ_COLOR_ORDER = [
+    "D","E","F","G","H","I","J","K","L","M","N","O",
+    "P","Q","R","S","T","U","V","W","X","Y","Z","PRE","STD"
+]
+
+FANCY_COLOR_ORDER = [
+    "YELLOW","BLUE","PINK","FANCY LIGHT YELLOW","FANCY YELLOW",
+    "FANCY INTENSE YELLOW","FANCY VIVID YELLOW",
+    "FANCY PINK","FANCY INTENSE PINK","FANCY VIVID PINK",
+    "FANCY BLUE","FANCY INTENSE BLUE","FANCY VIVID BLUE"
+]
+
+# ---------------- HTML ---------------- #
+
+HTML = """
+<h2>Universal File Sorter (Diamond MIS)</h2>
+
+<form method="post" enctype="multipart/form-data">
+    <input type="file" name="file" required>
+    <button type="submit">Sort File</button>
+</form>
+
+<p>Upload Excel/CSV → Get Sorted File Download</p>
+"""
+
+# ---------------- SORT ENGINE ---------------- #
+
+def apply_sort(df):
+
+    df.columns = [c.strip().lower() for c in df.columns]
+
+    def sort_col(col, order):
+        if col in df.columns:
+            df[col] = df[col].astype(str).str.upper()
+            df[col] = pd.Categorical(df[col], categories=order, ordered=True)
+
+    # Shape
+    sort_col("shape", SHAPE_ORDER)
+
+    # Size
+    sort_col("size range", SIZE_ORDER)
+
+    # Clarity
+    sort_col("clarity", CLARITY_ORDER)
+
+    # Color
+    if "color" in df.columns:
+        df["color"] = df["color"].astype(str).str.upper()
+
+        if df["color"].str.contains("FANCY").any():
+            order = FANCY_COLOR_ORDER
+        else:
+            order = DZ_COLOR_ORDER
+
+        df["color"] = pd.Categorical(df["color"], categories=order, ordered=True)
+
+    # sort by priority columns
+    sort_cols = [c for c in ["shape","size range","color","clarity"] if c in df.columns]
+    df = df.sort_values(sort_cols)
+
+    return df
+
+
+# ---------------- HOME ---------------- #
+
+@app.route("/", methods=["GET"])
+def home():
+    return render_template_string(HTML)
+
+
+# ---------------- PROCESS FILE ---------------- #
+
+@app.route("/", methods=["POST"])
+def process():
+
+    file = request.files["file"]
+
+    if file.filename.endswith(".csv"):
+        df = pd.read_csv(file)
+    else:
+        df = pd.read_excel(file)
+
+    df = apply_sort(df)
+
+    output = BytesIO()
+    df.to_excel(output, index=False)
+    output.seek(0)
+
+    return send_file(
+        output,
+        download_name="sorted_file.xlsx",
+        as_attachment=True
+    )
+
+
+# ---------------- RUN ---------------- #
+
+if __name__ == "__main__":
+    app.run(debug=True)