Package Exports
- llm-json-guard
- llm-json-guard/index.js
This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (llm-json-guard) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.
Readme
# llm-json-guard
Deterministic JSON repair and schema validation for LLM outputs.
Large Language Models frequently return malformed JSON containing:
- Missing quotes
- Trailing commas
- Invalid tokens
- Broken object structures
`llm-json-guard` repairs malformed JSON and optionally validates it against a JSON Schema — locally, instantly, and without network dependencies.
---
## Installation
```bash
npm install llm-json-guard
```
---
## Requirements
- Node.js 18+
No API keys.
No external services.
Runs fully local inside your application.
---
## Why Use This?
LLMs do not guarantee valid JSON. Even a single trailing comma can crash production systems.
This package provides:
- Deterministic JSON repair (no extra model calls)
- Confidence scoring based on repair intensity
- Optional JSON Schema validation
- Structured error responses
- Production-safe output handling
It acts as a reliability layer between your LLM and your business logic.
---
## Basic Usage
```js
import { LLMJsonGuard } from "llm-json-guard";
const guard = new LLMJsonGuard();
// Repair only
const sanitized = guard.sanitize("{name: 'Harsh', age: 21,}");
console.log(sanitized);
// Repair + Validate
const validated = guard.guard(
"{name: 'Harsh', age: 21,}",
{
type: "object",
properties: {
name: { type: "string" },
age: { type: "number" }
},
required: ["name", "age"]
}
);
console.log(validated);
```
---
## API Methods
### `sanitize(rawOutput)`
Repairs malformed JSON and safely parses it.
Returns:
- `success`
- `stage`
- `meta` (repair status + confidence)
- `data`
- `errors`
---
### `guard(rawOutput, schema)`
Repairs malformed JSON and validates it against a JSON Schema.
Returns:
- `validated` stage if schema passes
- `validation_failed` if schema check fails
- Structured validation errors
---
## Response Structure
Example successful response:
```json
{
"success": true,
"stage": "validated",
"meta": {
"repaired": true,
"confidence": 0.95
},
"data": {
"name": "Harsh",
"age": 21
},
"errors": []
}
```
---
## Failure Stages
The package clearly indicates failure states:
- `parse_failed` — JSON could not be repaired
- `repair_suspicious` — Repair heavily modified input
- `validation_failed` — Schema validation failed
This ensures your application can safely branch logic based on reliability.
---
## When To Use
- AI agents generating structured output
- RAG pipelines
- Backend systems consuming LLM JSON
- Automation workflows
- Webhook normalization
- Contract enforcement
If your system depends on structured AI output, this acts as a guardrail between the LLM and your production logic.
---
## License
MIT