Response Healing | Validate and Repair AI Model Responses | OpenRouter

The Response Healing plugin automatically validates and repairs malformed JSON responses from AI models. When models return imperfect formatting – missing brackets, trailing commas, markdown wrappers, or mixed text – this plugin attempts to repair the response so you receive valid, parseable JSON.

Overview

Response Healing provides:

Automatic JSON repair: Fixes missing brackets, commas, quotes, and other syntax errors
Markdown extraction: Extracts JSON from markdown code blocks

How It Works

The plugin activates for non-streaming requests when you use response_format with either type: "json_schema" or type: "json_object", and include the response-healing plugin in your plugins array. See the Complete Example below for a full implementation.

What Gets Fixed

The Response Healing plugin handles common issues in LLM responses:

JSON Syntax Errors

Input: Missing closing bracket

{"name": "Alice", "age": 30

Output: Fixed

1 {"name": "Alice", "age": 30}

Markdown Code Blocks

Input: Wrapped in markdown

```json
{"name": "Bob"}
```

Output: Extracted

1 {"name": "Bob"}

Mixed Text and JSON

Input: Text before JSON

Here's the data you requested:
{"name": "Charlie", "age": 25}

Output: Extracted

1 {"name": "Charlie", "age": 25}

Trailing Commas

Input: Invalid trailing comma

{"name": "David", "age": 35,}

Output: Fixed

1 {"name": "David", "age": 35}

Unquoted Keys

Input: JavaScript-style

{name: "Eve", age: 40}

Output: Fixed

1 {"name": "Eve", "age": 40}

Complete Example

1 const response = await fetch('https://openrouter.ai/api/v1/chat/completions', {
2   method: 'POST',
3   headers: {
4     Authorization: 'Bearer {{API_KEY_REF}}',
5     'Content-Type': 'application/json',
6   },
7   body: JSON.stringify({
8     model: '{{MODEL}}',
9     messages: [
10       {
11         role: 'user',
12         content: 'Generate a product listing with name, price, and description'
13       }
14     ],
15     response_format: {
16       type: 'json_schema',
17       json_schema: {
18         name: 'Product',
19         schema: {
20           type: 'object',
21           properties: {
22             name: {
23               type: 'string',
24               description: 'Product name'
25             },
26             price: {
27               type: 'number',
28               description: 'Price in USD'
29             },
30             description: {
31               type: 'string',
32               description: 'Product description'
33             }
34           },
35           required: ['name', 'price']
36         }
37       }
38     },
39     plugins: [
40       { id: 'response-healing' }
41     ]
42   }),
43 });
44 
45 const data = await response.json();
46 const product = JSON.parse(data.choices[0].message.content);
47 // The plugin attempts to repair malformed JSON syntax
48 console.log(product.name, product.price);

Limitations

Non-Streaming Requests Only

Response Healing only applies to non-streaming requests.

Will not repair all JSON

Some malformed JSON responses may still be unrepairable. In particular, if the response is truncated by max_tokens, the plugin will not be able to repair it.

1	const response = await fetch('https://openrouter.ai/api/v1/chat/completions', {
2	method: 'POST',
3	headers: {
4	Authorization: 'Bearer {{API_KEY_REF}}',
5	'Content-Type': 'application/json',
6	},
7	body: JSON.stringify({
8	model: '{{MODEL}}',
9	messages: [
10	{
11	role: 'user',
12	content: 'Generate a product listing with name, price, and description'
13	}
14	],
15	response_format: {
16	type: 'json_schema',
17	json_schema: {
18	name: 'Product',
19	schema: {
20	type: 'object',
21	properties: {
22	name: {
23	type: 'string',
24	description: 'Product name'
25	},
26	price: {
27	type: 'number',
28	description: 'Price in USD'
29	},
30	description: {
31	type: 'string',
32	description: 'Product description'
33	}
34	},
35	required: ['name', 'price']
36	}
37	}
38	},
39	plugins: [
40	{ id: 'response-healing' }
41	]
42	}),
43	});
44
45	const data = await response.json();
46	const product = JSON.parse(data.choices[0].message.content);
47	// The plugin attempts to repair malformed JSON syntax
48	console.log(product.name, product.price);