diff --git a/.env.example b/.env.example
index fe504eec8..bd61f8d25 100644
--- a/.env.example
+++ b/.env.example
@@ -109,6 +109,10 @@ CLOUDFLARE_IPS_RETRY_SLEEP_MS=250
 CLOUDFLARE_IPS_STORAGE_PATH=storage/app/cloudflare/trusted-proxies.json
 CLOUDFLARE_TRUST_REMOTE_ADDR_FALLBACK=true
 
+# Block configured indexer apps only when they proxy NZB downloads instead of redirecting to the downloader.
+BLOCK_PROXY_INDEXER_APPS=false
+BLOCK_PROXY_INDEXER_APP_USER_AGENTS=Prowlarr/,NZBHydra2
+
 APP_LOCALE=en
 APP_FALLBACK_LOCALE=en
 APP_FAKER_LOCALE=en_US
diff --git a/app/Http/Middleware/BlockAbusiveServices.php b/app/Http/Middleware/BlockAbusiveServices.php
index 254e8ab4f..551756dd6 100644
--- a/app/Http/Middleware/BlockAbusiveServices.php
+++ b/app/Http/Middleware/BlockAbusiveServices.php
@@ -17,6 +17,7 @@ use Symfony\Component\HttpFoundation\Response;
  * Blocks:
  * - AIOStreams (User-Agent based)
  * - UsenetStreamer (User-Agent based)
+ * - Configured indexer apps on public indexer API/RSS endpoints (User-Agent based, opt-in)
  * - Oracle Cloud (ASN: AS31898)
  * - Cloudflare WARP (ASN: AS13335)
  */
@@ -71,6 +72,16 @@ class BlockAbusiveServices
             return $this->blockedResponse('Access denied: Streaming services are not allowed.');
         }
 
+        if ($this->shouldBlockProxyIndexerApp($request, $userAgent)) {
+            Log::warning('Blocked proxy indexer app request', [
+                'ip' => $ip,
+                'user_agent' => $userAgent,
+                'uri' => $request->getRequestUri(),
+            ]);
+
+            return $this->blockedResponse('Access denied: Proxy indexer app access is not allowed.');
+        }
+
         // Check for blocked ASNs
         $asnInfo = $this->getAsnInfo($ip);
         if ($asnInfo !== null && isset($this->blockedAsns[$asnInfo['asn']])) {
@@ -107,6 +118,78 @@ class BlockAbusiveServices
         return false;
     }
 
+    /**
+     * Check whether an opt-in proxy indexer app block should apply.
+     */
+    protected function shouldBlockProxyIndexerApp(Request $request, string $userAgent): bool
+    {
+        if (! (bool) config('nntmux.block_proxy_indexer_apps', false)) {
+            return false;
+        }
+
+        if (! $this->isPublicIndexerEndpoint($request)) {
+            return false;
+        }
+
+        return $this->matchesAnyUserAgentPattern(
+            $userAgent,
+            $this->configuredProxyIndexerAppUserAgents()
+        );
+    }
+
+    /**
+     * Detect public indexer API/RSS endpoints while leaving unrelated requests alone.
+     */
+    protected function isPublicIndexerEndpoint(Request $request): bool
+    {
+        if ($request->is('api/v1/api') || $request->is('api/v2/*')) {
+            return true;
+        }
+
+        return $request->is('rss/*') && ! $request->is('rss/health');
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    protected function configuredProxyIndexerAppUserAgents(): array
+    {
+        $configured = config('nntmux.block_proxy_indexer_app_user_agents', []);
+
+        if (is_string($configured)) {
+            $configured = preg_split('/[\r\n,]+/', $configured) ?: [];
+        }
+
+        if (! is_array($configured)) {
+            Log::warning('Ignoring invalid proxy indexer app User-Agent configuration.', [
+                'configured_type' => get_debug_type($configured),
+            ]);
+
+            return [];
+        }
+
+        return array_values(array_filter(array_map(
+            static fn (mixed $pattern): string => is_string($pattern) ? trim($pattern) : '',
+            $configured,
+        )));
+    }
+
+    /**
+     * @param  array<int, string>  $patterns
+     */
+    protected function matchesAnyUserAgentPattern(string $userAgent, array $patterns): bool
+    {
+        $lowerUserAgent = strtolower($userAgent);
+
+        foreach ($patterns as $pattern) {
+            if (str_contains($lowerUserAgent, strtolower($pattern))) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Get ASN information for an IP address.
      * Uses ip-api.com with caching to minimize API calls.
diff --git a/config/nntmux.php b/config/nntmux.php
index 19f67a000..d4eef5c59 100644
--- a/config/nntmux.php
+++ b/config/nntmux.php
@@ -21,6 +21,8 @@ return [
     'purge_inactive_users' => env('PURGE_INACTIVE_USERS', false),
     'purge_inactive_users_days' => env('PURGE_INACTIVE_USERS_DAYS', 180),
     'mysql_search_fallback' => env('MYSQL_SEARCH_FALLBACK', false), // Disable MySQL LIKE fallback when Manticore/Elasticsearch return no results
+    'block_proxy_indexer_apps' => (bool) env('BLOCK_PROXY_INDEXER_APPS', false),
+    'block_proxy_indexer_app_user_agents' => env('BLOCK_PROXY_INDEXER_APP_USER_AGENTS', 'Prowlarr/,NZBHydra2'),
 
     /*
     |--------------------------------------------------------------------------