diff --git a/.env.example b/.env.example
index bcef7fc6..9c932365 100644
--- a/.env.example
+++ b/.env.example
@@ -37,6 +37,9 @@ UVICORN_PORT = 8000
 # SINGBOX_SUBSCRIPTION_TEMPLATE="singbox/default.json"
 # MUX_TEMPLATE="mux/default.json"
 
+## Enable JSON support for compatible clients to use mux, fragment, etc. Default is null, meaning false.
+# USE_CUSTOM_JSON_DEFAULT="True" 
+
 ## Set headers for subscription
 # SUB_PROFILE_TITLE = "Susbcription"
 # SUB_SUPPORT_URL = "https://t.me/support"
diff --git a/app/views/subscription.py b/app/views/subscription.py
index 844d9535..8c1d21d9 100644
--- a/app/views/subscription.py
+++ b/app/views/subscription.py
@@ -16,7 +16,8 @@
     SUB_SUPPORT_URL,
     SUB_UPDATE_INTERVAL,
     SUBSCRIPTION_PAGE_TEMPLATE,
-    XRAY_SUBSCRIPTION_PATH
+    XRAY_SUBSCRIPTION_PATH,
+    USE_CUSTOM_JSON_DEFAULT
 )
 
 
@@ -93,7 +94,7 @@ def get_subscription_user_info(user: UserResponse) -> dict:
 
     elif re.match('^v2rayNG/(\d+\.\d+\.\d+)', user_agent):
         version_str = re.match('^v2rayNG/(\d+\.\d+\.\d+)', user_agent).group(1)
-        if LooseVersion(version_str) >= LooseVersion("1.8.16"):
+        if LooseVersion(version_str) >= LooseVersion("1.8.16") and USE_CUSTOM_JSON_DEFAULT:
             conf = generate_subscription(user=user, config_format="v2ray-json", as_base64=False)
             return Response(content=conf, media_type="application/json", headers=response_headers)
         else:
diff --git a/config.py b/config.py
index fcfc8cc1..ec415b1a 100755
--- a/config.py
+++ b/config.py
@@ -50,6 +50,7 @@
 SINGBOX_SUBSCRIPTION_TEMPLATE = config("SINGBOX_SUBSCRIPTION_TEMPLATE", default="singbox/default.json")
 MUX_TEMPLATE = config("MUX_TEMPLATE", default="mux/default.json")
 V2RAY_SUBSCRIPTION_TEMPLATE = config("V2RAY_SUBSCRIPTION_TEMPLATE", default="v2ray/default.json")
+USE_CUSTOM_JSON_DEFAULT = config("USE_CUSTOM_JSON_DEFAULT", default="")
 
 ACTIVE_STATUS_TEXT = config("ACTIVE_STATUS_TEXT", default="Active")
 EXPIRED_STATUS_TEXT = config("EXPIRED_STATUS_TEXT", default="Expired")