diff --git a/backend/scripts/pruefe_salden.py b/backend/scripts/pruefe_salden.py
new file mode 100755
index 0000000..da87059
--- /dev/null
+++ b/backend/scripts/pruefe_salden.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""Schlüsselt auf, woraus sich jeder Kontostand zusammensetzt.
+
+Saldo = Anfangssaldo + Einnahmen - Ausgaben - Transfers raus + Transfers rein.
+Stimmt ein Kontostand nicht, liegt es fast immer an einer dieser fünf Zahlen –
+oder an einem doppelt eingelesenen Auszug. Beides zeigt dieses Skript.
+
+Aufruf:  pruefe_salden.py [pfad-zur-db]
+"""
+import sqlite3
+import sys
+from collections import Counter
+
+DB = sys.argv[1] if len(sys.argv) > 1 else "/var/lib/certain-finance/app.db"
+con = sqlite3.connect(f"file:{DB}?mode=ro", uri=True)
+con.row_factory = sqlite3.Row
+
+
+def eins(sql, *p):
+    return con.execute(sql, p).fetchone()[0] or 0
+
+
+def geld(c, w=""):
+    return f"{c / 100:,.2f}".replace(",", "'") + (f" {w}" if w else "")
+
+
+print(f"Datenbank: {DB}\n")
+
+for a in con.execute("SELECT id, name, currency, opening_balance_cents FROM accounts "
+                     "WHERE is_archived = 0 ORDER BY position, id"):
+    ein = eins("SELECT SUM(amount_cents) FROM transactions WHERE account_id=? AND type='income'", a["id"])
+    aus = eins("SELECT SUM(amount_cents) FROM transactions WHERE account_id=? AND type='expense'", a["id"])
+    raus = eins("SELECT SUM(amount_cents) FROM transactions WHERE account_id=? AND type='transfer'", a["id"])
+    rein = eins("SELECT SUM(COALESCE(to_amount_cents, amount_cents)) FROM transactions "
+                "WHERE to_account_id=? AND type='transfer'", a["id"])
+    saldo = a["opening_balance_cents"] + ein - aus - raus + rein
+    anz = eins("SELECT COUNT(*) FROM transactions WHERE account_id=? OR to_account_id=?", a["id"], a["id"])
+    spanne = con.execute("SELECT MIN(date), MAX(date) FROM transactions WHERE account_id=?", (a["id"],)).fetchone()
+
+    print(f"=== {a['name']}  ({a['currency']}, id {a['id']}) ===")
+    print(f"  Anfangssaldo     {geld(a['opening_balance_cents']):>14}")
+    print(f"  + Einnahmen      {geld(ein):>14}")
+    print(f"  - Ausgaben       {geld(aus):>14}")
+    print(f"  - Transfers raus {geld(raus):>14}")
+    print(f"  + Transfers rein {geld(rein):>14}")
+    print(f"  = SALDO          {geld(saldo, a['currency']):>14}")
+    print(f"  {anz} Buchungen, {spanne[0] or '–'} bis {spanne[1] or '–'}")
+
+    # Doppelte Auszüge erkennen: gleicher Dateiname mehrfach gebucht.
+    batches = con.execute(
+        "SELECT filename, status, imported_count, created_at FROM import_batches "
+        "WHERE account_id=? ORDER BY created_at", (a["id"],)).fetchall()
+    namen = Counter(b["filename"] for b in batches if b["status"] == "committed")
+    for b in batches:
+        marke = "  <-- Datei mehrfach gebucht!" if b["status"] == "committed" and namen[b["filename"]] > 1 else ""
+        print(f"    [{b['status']:<9}] {b['imported_count']:>4} aus {b['filename'][:44]}{marke}")
+
+    # Buchungen, die sich in Datum+Betrag+Empfänger gleichen.
+    dop = con.execute(
+        "SELECT date, amount_cents, COALESCE(payee,''), COUNT(*) n FROM transactions "
+        "WHERE account_id=? GROUP BY 1,2,3 HAVING n > 1 ORDER BY n DESC LIMIT 5", (a["id"],)).fetchall()
+    if dop:
+        summe = eins("SELECT SUM(amount_cents * (n-1)) FROM (SELECT amount_cents, COUNT(*) n "
+                     "FROM transactions WHERE account_id=? GROUP BY date, amount_cents, COALESCE(payee,'') "
+                     "HAVING n > 1)", a["id"])
+        print(f"    Mehrfach vorhanden: {len(dop)} Kombinationen, Summe der Überzähligen {geld(summe)}")
+        for d in dop:
+            print(f"      {d[0]}  {geld(d[1]):>10}  {d[2][:34]:<34} x{d[3]}")
+    print()