📚 Documentation

Overview

JSON Guardian is a high-performance REST API that solves a critical problem in AI applications: LLMs frequently produce malformed or schema-violating JSON, causing production failures. This service provides:

• Validation – Verify JSON against schemas (JSON Schema Draft 7)
• Repair – Automatically fix common JSON syntax errors
• Enforcement – Combined validation + repair in one call

Base URL: https://api.jsonguardian.com

Quick Start

1. Health check

curl https://api.jsonguardian.com/health
# Output: OK

2. Validate JSON

curl -X POST https://api.jsonguardian.com/api/v1/validate \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-key" \
  -d '{
    "schema": {
      "type": "object",
      "properties": {
        "name": {"type": "string"},
        "age": {"type": "number"}
      },
      "required": ["name", "age"]
    },
    "data": "{\"name\": \"John\", \"age\": 30}"
  }'

3. Repair broken JSON

curl -X POST https://api.jsonguardian.com/api/v1/repair \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-key" \
  -d '{"data": "{\"name\": \"John\", \"age\": 30,}"}'

API Endpoints

Authentication

All API calls (except /health) require an API key in the header:

X-API-Key: your-api-key

Get your API key from the dashboard after signing up.

Validation Endpoint

Request body

{
  "schema": {
    "type": "object",
    "properties": {
      "name": {"type": "string"},
      "age": {"type": "number"}
    },
    "required": ["name", "age"]
  },
  "data": "{\"name\": \"John\", \"age\": 30}"
}

Response (success)

{
  "valid": true,
  "errors": [],
  "parsed_data": {
    "name": "John",
    "age": 30
  }
}

Response (validation error)

{
  "valid": false,
  "errors": [
    {
      "path": "/age",
      "message": "\"thirty\" is not of type \"number\""
    }
  ],
  "parsed_data": null
}

Repair Endpoint

Request body

{
  "data": "{\"name\": \"John\", \"age\": 30,}"
}

Notice the trailing comma, which is invalid JSON.

Response

{
  "success": true,
  "original": "{\"name\": \"John\", \"age\": 30,}",
  "repaired": "{\n  \"name\": \"John\",\n  \"age\": 30\n}",
  "repaired_data": {
    "name": "John",
    "age": 30
  }
}

What gets repaired

• Trailing commas: {"a": 1,} → {"a": 1}
• Missing closing braces
• Single quotes: {'a': 'b'} → {"a": "b"}
• Unquoted keys: {name: "John"} → {"name": "John"}
• Escape sequence issues

Enforce Endpoint

Combines repair and validation in one call. First repairs the JSON, then validates against the schema.

{
  "schema": {
    "type": "object",
    "properties": {
      "name": {"type": "string"}
    }
  },
  "data": "{\"name\": \"John\",}"
}

Error Handling

Code Examples

Choose your language. More languages can be added here without changing the page layout.

async function validateJSON(schema, data) {
  const response = await fetch('https://api.jsonguardian.com/api/v1/validate', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-API-Key': 'your-api-key'
    },
    body: JSON.stringify({ schema, data })
  });
  return await response.json();
}

const schema = {
  type: "object",
  properties: {
    name: { type: "string" },
    age: { type: "number" }
  },
  required: ["name", "age"]
};

const result = await validateJSON(schema, '{"name": "John", "age": 30}');

if (result.valid) {
  console.log("Valid JSON:", result.parsed_data);
} else {
  console.log("Validation errors:", result.errors);
}

import requests

class JSONGuardian:
    def __init__(self, api_key):
        self.api_key = api_key
        self.base_url = "https://api.jsonguardian.com/api/v1"

    def validate(self, schema, data):
        response = requests.post(
            f"{self.base_url}/validate",
            headers={
                "Content-Type": "application/json",
                "X-API-Key": self.api_key
            },
            json={"schema": schema, "data": data}
        )
        return response.json()

    def repair(self, data):
        response = requests.post(
            f"{self.base_url}/repair",
            headers={
                "Content-Type": "application/json",
                "X-API-Key": self.api_key
            },
            json={"data": data}
        )
        return response.json()

# Usage
client = JSONGuardian("your-api-key")

schema = {
    "type": "object",
    "properties": {
        "name": {"type": "string"},
        "age": {"type": "number"}
    },
    "required": ["name", "age"]
}

result = client.validate(schema, '{"name": "John", "age": 30}')

if result["valid"]:
    print("Valid:", result["parsed_data"])
else:
    print("Errors:", result["errors"])

# Validate
curl -X POST https://api.jsonguardian.com/api/v1/validate \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-key" \
  -d '{
    "schema": {
      "type": "object",
      "properties": {
        "name": {"type": "string"},
        "age": {"type": "number"}
      },
      "required": ["name", "age"]
    },
    "data": "{\"name\": \"John\", \"age\": 30}"
  }'

# Repair
curl -X POST https://api.jsonguardian.com/api/v1/repair \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-key" \
  -d '{"data": "{\"name\": \"John\", \"age\": 30,}"}'

API key tiers

Available tiers: free (10k/mo), starter (100k/mo), pro (1M/mo). Create keys from your dashboard or via the API.

curl -X POST https://api.jsonguardian.com/api/v1/keys \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-key" \
  -d '{
    "name": "My Production Key",
    "tier": "pro"
  }'