diff --git a/.env.example b/.env.example
index 9d128a5..f0b861c 100644
--- a/.env.example
+++ b/.env.example
@@ -17,6 +17,11 @@ SESSION_COOKIE_SECRET=please-change-me-in-prod-at-least-32-chars
 # --- Cron Bearer (Story 2.6 + 5.1 + 6.3) ---
 CRON_BEARER_TOKEN=please-change-me-in-prod
 
+# --- Backup-Sidecar (Story 6.3, nur Prod) ---
+# Täglicher pg_dump im service "backup". Beide optional (Defaults: 03 / 14).
+# BACKUP_HOUR=03
+# BACKUP_RETENTION_DAYS=14
+
 # --- App ---
 NODE_ENV=development
 LOG_LEVEL=info
diff --git a/docker-compose.yml b/docker-compose.yml
index 0868227..42bcb8c 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -21,6 +21,33 @@ services:
       timeout: 5s
       retries: 5
 
+  # Backup-Sidecar: täglicher pg_dump des postgres-Service nach cockpit_backups.
+  # Nutzt scripts/backup.sh (Custom-Format-Dump + Retention + API-Heartbeat),
+  # getaktet von scripts/backup-loop.sh. Stock postgres-Image → pg_dump passt
+  # versionsgenau (16) zur DB. Restore: siehe docs/operations.md.
+  backup:
+    image: postgres:16-alpine
+    container_name: cockpit-backup
+    restart: unless-stopped
+    depends_on:
+      postgres:
+        condition: service_healthy
+    environment:
+      POSTGRES_USER: ${POSTGRES_USER:-cockpit}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
+      POSTGRES_DB: ${POSTGRES_DB:-cockpit}
+      PGHOST: postgres
+      API_URL: http://api:3000
+      CRON_BEARER_TOKEN: ${CRON_BEARER_TOKEN}
+      BACKUP_HOUR: ${BACKUP_HOUR:-03}
+      BACKUP_RETENTION_DAYS: ${BACKUP_RETENTION_DAYS:-14}
+      TZ: Europe/Berlin
+    volumes:
+      - cockpit_backups:/backups
+      - ./scripts/backup.sh:/usr/local/bin/backup.sh:ro
+      - ./scripts/backup-loop.sh:/usr/local/bin/backup-loop.sh:ro
+    entrypoint: ['/bin/sh', '/usr/local/bin/backup-loop.sh']
+
   api:
     build:
       context: .
diff --git a/docs/operations.md b/docs/operations.md
index c4e1aa9..2c4116f 100644
--- a/docs/operations.md
+++ b/docs/operations.md
@@ -54,14 +54,35 @@ docker compose exec api node -e "import('@cockpit/db/client').then(async ({ crea
 
 ## Backups (Story 6.3)
 
-Tägliches `pg_dump` via Cron-Endpoint `POST /internal/cron/pg-dump-backup` mit Bearer-Token.
-14 Tage Retention. Restore-Drill quartalsweise.
+Tägliches `pg_dump` läuft im **Backup-Sidecar** (`docker-compose.yml` service `backup`):
+`scripts/backup-loop.sh` triggert `scripts/backup.sh` einmal pro Tag um
+`BACKUP_HOUR` (Default 03:00 Europe/Berlin). Dump im **Custom-Format** (`-Fc`,
+bereits komprimiert) nach `cockpit_backups:/backups` als `cockpit-<ts>.dump`.
+Retention `BACKUP_RETENTION_DAYS` (Default 14). Nach jedem Lauf ein Heartbeat an
+`POST /internal/cron/pg-dump-backup` (nur Logging — der Endpoint macht **kein**
+Backup). Restore-Drill quartalsweise.
+
+Konfiguration (optional, in `.env.production`): `BACKUP_HOUR`, `BACKUP_RETENTION_DAYS`.
+
+```bash
+# Status / letztes Backup ansehen
+docker compose logs --tail=20 backup
+docker compose exec backup ls -lh /backups
+
+# Sofort ein Backup auslösen (außer der Reihe)
+docker compose exec backup /usr/local/bin/backup.sh
+```
 
 ### Restore-Anleitung
 
 1. API stoppen: `docker compose stop api`
-2. Backup aus `/backups` auswählen.
-3. Restore in temporäre DB: `docker compose exec postgres pg_restore -U cockpit -d cockpit_restore /backups/<file>.sql.gz`
+2. Backup aus `/backups` auswählen (`docker compose exec postgres ls -lh /backups`).
+3. Restore in temporäre DB:
+   ```bash
+   docker compose exec postgres createdb -U cockpit cockpit_restore
+   docker compose exec postgres pg_restore -U cockpit -d cockpit_restore /backups/<file>.dump
+   ```
+   (In die Produktiv-DB stattdessen mit `--clean --if-exists -d cockpit`.)
 4. Smoke-Test: `curl http://localhost:3000/api/health`
 5. API wieder starten: `docker compose start api`
 
diff --git a/scripts/backup-loop.sh b/scripts/backup-loop.sh
new file mode 100755
index 0000000..2cab1bd
--- /dev/null
+++ b/scripts/backup-loop.sh
@@ -0,0 +1,19 @@
+#!/bin/sh
+# Minimaler Tages-Scheduler für den Backup-Sidecar: führt backup.sh einmal
+# täglich zur Stunde BACKUP_HOUR (Container-TZ = Europe/Berlin) aus.
+#
+# Bewusst kein cron: ein simpler Poll-Loop erbt das Container-Environment
+# zuverlässig (POSTGRES_PASSWORD u. a.) und hat keine busybox-cron-Eigenheiten.
+
+set -eu
+
+HOUR="${BACKUP_HOUR:-03}"
+echo "Backup-Sidecar aktiv — täglich um ${HOUR}:00 (TZ=${TZ:-UTC}), Retention ${BACKUP_RETENTION_DAYS:-14} Tage."
+
+while true; do
+  if [ "$(date +%H)" = "$HOUR" ] && [ "$(date +%M)" = "00" ]; then
+    /usr/local/bin/backup.sh || echo "Backup fehlgeschlagen (Exit $?)" >&2
+    sleep 61 # diese Minute überspringen, damit nicht doppelt ausgelöst wird
+  fi
+  sleep 30
+done
diff --git a/scripts/backup.sh b/scripts/backup.sh
index 0c04f43..c47f5ad 100755
--- a/scripts/backup.sh
+++ b/scripts/backup.sh
@@ -1,21 +1,31 @@
 #!/bin/sh
-# Tägliches pg_dump in /backups, 14 Tage Retention.
-# Läuft im Postgres-Container via System-Cron.
+# pg_dump des Cockpit-Postgres nach /backups. Custom-Format (-Fc): bereits
+# komprimiert UND erlaubt selektives pg_restore — daher KEIN zusätzliches gzip.
+#
+# Läuft im Backup-Sidecar (docker-compose.yml service "backup") gegen den
+# postgres-Service (PGHOST). Einmal pro Tag getriggert von backup-loop.sh.
+# Manuell ausführbar: `docker compose exec backup /usr/local/bin/backup.sh`.
 
 set -eu
 
+PGHOST="${PGHOST:-postgres}"
+PGUSER="${POSTGRES_USER:-cockpit}"
+PGDATABASE="${POSTGRES_DB:-cockpit}"
+RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-14}"
 DATE=$(date +%Y%m%d-%H%M%S)
-OUT="/backups/cockpit-${DATE}.sql.gz"
+OUT="/backups/cockpit-${DATE}.dump"
 mkdir -p /backups
 
-pg_dump -U "${POSTGRES_USER:-cockpit}" -d "${POSTGRES_DB:-cockpit}" -Fc | gzip > "$OUT"
-echo "Backup written: $OUT"
+export PGPASSWORD="${POSTGRES_PASSWORD:-}"
+pg_dump -h "$PGHOST" -U "$PGUSER" -d "$PGDATABASE" -Fc -f "$OUT"
+echo "Backup geschrieben: $OUT ($(du -h "$OUT" | cut -f1))"
 
-# Retention: lösche Dumps älter als 14 Tage.
-find /backups -type f -name "cockpit-*.sql.gz" -mtime +14 -delete
+# Retention: Dumps älter als N Tage löschen.
+find /backups -type f -name 'cockpit-*.dump' -mtime "+${RETENTION_DAYS}" -delete
 
-# Heartbeat an API (logging).
-if [ -n "${CRON_BEARER_TOKEN:-}" ] && [ -n "${API_URL:-}" ]; then
+# Heartbeat an die API (nur Observability/Logging — macht selbst kein Backup).
+API_URL="${API_URL:-http://api:3000}"
+if [ -n "${CRON_BEARER_TOKEN:-}" ]; then
   wget -q --header="Authorization: Bearer ${CRON_BEARER_TOKEN}" \
     -O- "${API_URL}/internal/cron/pg-dump-backup" || true
 fi