diff --git a/admin.go b/admin.go
index 0ae1ff4..61f03c4 100644
--- a/admin.go
+++ b/admin.go
@@ -3,6 +3,7 @@ package main
 import (
 	"database/sql"
 	"encoding/json"
+	"log"
 	"net/http"
 	"strconv"
 	"strings"
@@ -60,6 +61,69 @@ func handleAdminUpdateRepeater(db *sql.DB) http.HandlerFunc {
 	}
 }
 
+func handleBackfillBM(db *sql.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
+			return
+		}
+
+		bmSet := loadBMRepeaters("")
+		if len(bmSet) == 0 {
+			http.Error(w, `{"error":"could not load BM repeaters"}`, http.StatusInternalServerError)
+			return
+		}
+		log.Printf("BM backfill: downloaded %d BM callsigns", len(bmSet))
+
+		rows, err := db.Query("SELECT id, callsign FROM repeaters WHERE NOT networks @> ARRAY['Brandmeister']")
+		if err != nil {
+			http.Error(w, `{"error":"database query failed"}`, http.StatusInternalServerError)
+			return
+		}
+		defer rows.Close()
+
+		var ids []int
+		for rows.Next() {
+			var id int
+			var callsign string
+			if err := rows.Scan(&id, &callsign); err != nil {
+				continue
+			}
+			if bmSet[strings.ToUpper(strings.TrimSpace(callsign))] {
+				ids = append(ids, id)
+			}
+		}
+
+		if len(ids) == 0 {
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(map[string]interface{}{"updated": 0})
+			return
+		}
+
+		tx, err := db.Begin()
+		if err != nil {
+			http.Error(w, `{"error":"transaction failed"}`, http.StatusInternalServerError)
+			return
+		}
+
+		updated := 0
+		for _, id := range ids {
+			if _, err := tx.Exec("UPDATE repeaters SET networks = array_append(networks, 'Brandmeister') WHERE id = $1", id); err == nil {
+				updated++
+			}
+		}
+
+		if err := tx.Commit(); err != nil {
+			http.Error(w, `{"error":"commit failed"}`, http.StatusInternalServerError)
+			return
+		}
+
+		log.Printf("BM backfill: updated %d repeaters", updated)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]interface{}{"updated": updated})
+	}
+}
+
 func handleAdminRepeaters(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodGet {
diff --git a/main.go b/main.go
index 4c12b54..24eb84e 100644
--- a/main.go
+++ b/main.go
@@ -44,6 +44,7 @@ func main() {
 		adminAPI := http.NewServeMux()
 		adminAPI.HandleFunc("/admin/api/repeaters", handleAdminRepeaters(db))
 		adminAPI.HandleFunc("/admin/api/repeaters/update", handleAdminUpdateRepeater(db))
+		adminAPI.HandleFunc("/admin/api/repeaters/backfill-bm", handleBackfillBM(db))
 		mux.Handle("/admin/api/", adminAuth(adminToken, adminAPI))
 		log.Println("Admin interface enabled at /admin/")
 	}
diff --git a/static/admin.html b/static/admin.html
index 588eac0..d401c35 100644
--- a/static/admin.html
+++ b/static/admin.html
@@ -171,6 +171,24 @@
 
         .logout-btn:hover { background: var(--hover-bg); }
 
+        .topbar-btn {
+            background: none;
+            border: 1px solid var(--border);
+            border-radius: 6px;
+            padding: 6px 12px;
+            font-size: 12px;
+            color: var(--text-muted);
+            cursor: pointer;
+            white-space: nowrap;
+        }
+
+        .topbar-btn:hover { background: var(--hover-bg); }
+
+        .topbar-btn:disabled {
+            opacity: 0.5;
+            cursor: default;
+        }
+
         .table-wrap {
             overflow-x: auto;
             padding: 16px 24px;
@@ -456,6 +474,7 @@
         <h1>DMRmap Admin</h1>
         <input type="text" class="search-input" id="search-input" placeholder="Search callsign, city, country, network..." />
         <span class="topbar-info" id="total-info"></span>
+        <button class="topbar-btn" id="backfill-bm-btn">Backfill BM</button>
         <button class="logout-btn" id="logout-btn">Logout</button>
     </div>
     <div class="table-wrap">
@@ -904,6 +923,26 @@
         showLogin();
     });
 
+    // Backfill BM
+    var backfillBtn = document.getElementById("backfill-bm-btn");
+    backfillBtn.addEventListener("click", function () {
+        if (!confirm("Download BrandMeister repeater list and add the Brandmeister network tag to all matching repeaters that are missing it?")) return;
+        backfillBtn.disabled = true;
+        backfillBtn.textContent = "Running...";
+        apiFetch("/admin/api/repeaters/backfill-bm", { method: "POST" })
+            .then(function (data) {
+                backfillBtn.disabled = false;
+                backfillBtn.textContent = "Backfill BM";
+                alert("Updated " + data.updated + " repeater" + (data.updated !== 1 ? "s" : "") + ".");
+                if (data.updated > 0) fetchRepeaters();
+            })
+            .catch(function (err) {
+                backfillBtn.disabled = false;
+                backfillBtn.textContent = "Backfill BM";
+                if (err.message !== "unauthorized") alert("Backfill failed: " + err.message);
+            });
+    });
+
     // Search
     searchInput.addEventListener("input", function () {
         clearTimeout(debounceTimer);