diff --git a/backend/src/api/nft_manager.py b/backend/src/api/nft_manager.py
index e8ebe13..d2beb50 100644
--- a/backend/src/api/nft_manager.py
+++ b/backend/src/api/nft_manager.py
@@ -61,10 +61,34 @@ class NftManager:
         Try to obtain nft -j list ruleset (JSON). Returns parsed JSON dict on success.
         Raises NftError on failure or when output cannot be parsed as JSON.
         """
-        res = self.nft.json_cmd("list ruleset")
-        if res[0] != 0:
-            raise NftError(f"nft list ruleset failed: {res[2]}")
-        return json.loads(res[1])
+        # prefer using json_cmd when available for a clean tuple (rc, out, err)
+        try:
+            res = self.nft.json_cmd("list ruleset")
+            if not isinstance(res, (list, tuple)) or len(res) < 3:
+                raise Exception("unexpected json_cmd result shape")
+            if res[0] != 0:
+                raise NftError(f"nft list ruleset failed: {res[2]}")
+            return json.loads(res[1])
+        except AttributeError:
+            # fallback to textual cmd + json.loads if json_cmd is not available
+            cmd_variants = ["list ruleset -j", "list ruleset"]
+            last_err = None
+            for c in cmd_variants:
+                r = self.cmd(c)
+                if r["rc"] != 0:
+                    last_err = r["stderr"]
+                    continue
+                out = r["stdout"]
+                if not out:
+                    last_err = "empty output"
+                    continue
+                try:
+                    parsed = json.loads(out)
+                    return parsed
+                except json.JSONDecodeError as e:
+                    last_err = f"json decode error: {e}"
+                    continue
+            raise NftError(f"unable to get JSON ruleset: {last_err}")
 
     def list_chain_text(self, family: str, table: str, chain: str) -> str:
         """
@@ -714,7 +738,9 @@ def list_rules():
         except Exception as e:
             logger.debug("list_rules: populate_text_from_chain_text failed: %s", e)
 
-        ruleset_model = json.dumps(RulesetModel.parse_obj(custom))
+        # IMPORTANT: return the parsed RulesetModel (not a JSON string) so FastAPI/Pydantic
+        # will serialize the structure properly without double-escaping.
+        ruleset_model = RulesetModel.parse_obj(custom)
         return RulesetOut(ruleset=ruleset_model)
     except NftError as e:
         logger.exception("list_rules failed")