diff --git a/nodes/json_builder.py b/nodes/json_builder.py
new file mode 100644
index 0000000..dd72cb1
--- /dev/null
+++ b/nodes/json_builder.py
@@ -0,0 +1,66 @@
+import json
+import re
+from typing import Tuple, Optional
+
+
+class JSONBuilder:
+    """
+    Build JSON object from multiple key-value inputs.
+    """
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {},
+            "optional": {
+                "key_1": ("STRING", {"default": ""}),
+                "value_1": ("STRING", {"default": "", "forceInput": True}),
+                "key_2": ("STRING", {"default": ""}),
+                "value_2": ("STRING", {"default": "", "forceInput": True}),
+                "key_3": ("STRING", {"default": ""}),
+                "value_3": ("STRING", {"default": "", "forceInput": True}),
+                "key_4": ("STRING", {"default": ""}),
+                "value_4": ("STRING", {"default": "", "forceInput": True}),
+                "key_5": ("STRING", {"default": ""}),
+                "value_5": ("STRING", {"default": "", "forceInput": True}),
+            }
+        }
+
+    RETURN_TYPES = ("STRING",)
+    RETURN_NAMES = ("json_string",)
+    FUNCTION = "build"
+    CATEGORY = "🚦ComfyUI_LLMs_Toolkit/JSON"
+
+    def build(
+        self,
+        key_1: str = "", value_1: str = "",
+        key_2: str = "", value_2: str = "",
+        key_3: str = "", value_3: str = "",
+        key_4: str = "", value_4: str = "",
+        key_5: str = "", value_5: str = ""
+    ) -> Tuple[str]:
+        """Build JSON from key-value pairs."""
+        result = {}
+        
+        pairs = [
+            (key_1, value_1), (key_2, value_2), (key_3, value_3),
+            (key_4, value_4), (key_5, value_5)
+        ]
+        
+        for key, value in pairs:
+            if key and key.strip():
+                # Try to parse value as JSON, otherwise use as string
+                try:
+                    parsed_value = json.loads(value)
+                    result[key.strip()] = parsed_value
+                except (json.JSONDecodeError, TypeError):
+                    result[key.strip()] = value
+        
+        json_str = json.dumps(result, ensure_ascii=False, indent=2)
+        print(f"# [🚦 LLMs_Toolkit] built JSON with {len(result)} keys")
+        return (json_str,)
+
+
+# Register the node
+NODE_CLASS_MAPPINGS = {"JSONBuilder": JSONBuilder}
+NODE_DISPLAY_NAME_MAPPINGS = {"JSONBuilder": "JSON Builder"}
diff --git a/nodes/json_extractor.py b/nodes/json_extractor.py
index 14ec0bd..18ef792 100644
--- a/nodes/json_extractor.py
+++ b/nodes/json_extractor.py
@@ -12,8 +12,7 @@ class JSONExtractor:
         return {
             "required": {
                 "json_string": ("STRING", {
-                    "multiline": True,
-                    "default": "{}"
+                    "forceInput": True
                 }),
                 "key": ("STRING", {
                     "default": "",
diff --git a/nodes/json_fixer.py b/nodes/json_fixer.py
new file mode 100644
index 0000000..02d67a0
--- /dev/null
+++ b/nodes/json_fixer.py
@@ -0,0 +1,111 @@
+import json
+import re
+from typing import Tuple
+
+
+class JSONFixer:
+    """
+    Fix malformed JSON from LLM outputs.
+    
+    Common issues fixed:
+    - Trailing commas
+    - Single quotes instead of double quotes
+    - Unquoted keys
+    - Missing quotes around string values
+    - Markdown code block wrappers
+    - Extra text before/after JSON
+    """
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "text": ("STRING", {"forceInput": True})
+            }
+        }
+
+    RETURN_TYPES = ("STRING",)
+    RETURN_NAMES = ("fixed_json",)
+    FUNCTION = "fix"
+    CATEGORY = "🚦ComfyUI_LLMs_Toolkit/JSON"
+
+    def fix(self, text: str) -> Tuple[str]:
+        """
+        Attempt to fix malformed JSON.
+        
+        Args:
+            text: Raw text that should contain JSON
+            
+        Returns:
+            Fixed JSON string, or error message if unfixable
+        """
+        original = text
+        
+        # Step 1: Try direct parse first (already valid)
+        try:
+            parsed = json.loads(text)
+            print(f"# [🚦 LLMs_Toolkit] JSON already valid")
+            return (json.dumps(parsed, ensure_ascii=False),)
+        except json.JSONDecodeError:
+            pass
+        
+        # Step 2: Extract JSON from markdown code blocks
+        code_block_pattern = r"```(?:json)?\s*([\s\S]*?)```"
+        matches = re.findall(code_block_pattern, text)
+        if matches:
+            text = matches[0].strip()
+        
+        # Step 3: Find JSON-like content (starts with { or [)
+        json_pattern = r'(\{[\s\S]*\}|\[[\s\S]*\])'
+        json_matches = re.findall(json_pattern, text)
+        if json_matches:
+            # Try each match
+            for match in json_matches:
+                text = match.strip()
+                try:
+                    parsed = json.loads(text)
+                    print(f"# [🚦 LLMs_Toolkit] extracted JSON from text")
+                    return (json.dumps(parsed, ensure_ascii=False),)
+                except json.JSONDecodeError:
+                    pass
+        
+        # Step 4: Apply common fixes
+        fixed = text
+        
+        # Remove trailing commas before } or ]
+        fixed = re.sub(r',\s*([}\]])', r'\1', fixed)
+        
+        # Replace single quotes with double quotes (careful with apostrophes)
+        # Only replace quotes that look like JSON string delimiters
+        fixed = re.sub(r"'([^']*)':", r'"\1":', fixed)  # Keys
+        fixed = re.sub(r":\s*'([^']*)'([,}\]])", r': "\1"\2', fixed)  # Values
+        
+        # Try parse after fixes
+        try:
+            parsed = json.loads(fixed)
+            print(f"# [🚦 LLMs_Toolkit] fixed JSON (trailing commas, quotes)")
+            return (json.dumps(parsed, ensure_ascii=False),)
+        except json.JSONDecodeError as e:
+            pass
+        
+        # Step 5: Last resort - try to find any valid JSON substring
+        for i in range(len(original)):
+            if original[i] in '{[':
+                for j in range(len(original), i, -1):
+                    try:
+                        candidate = original[i:j]
+                        parsed = json.loads(candidate)
+                        print(f"# [🚦 LLMs_Toolkit] extracted valid JSON substring")
+                        return (json.dumps(parsed, ensure_ascii=False),)
+                    except json.JSONDecodeError:
+                        continue
+        
+        # Failed to fix
+        error_msg = f"Unable to fix JSON: {str(e)}"
+        print(f"# [🚦 LLMs_Toolkit] ✗ {error_msg}")
+        return (error_msg,)
+
+
+# Register the node
+NODE_CLASS_MAPPINGS = {"JSONFixer": JSONFixer}
+NODE_DISPLAY_NAME_MAPPINGS = {"JSONFixer": "JSON Fixer"}