JSON Validator API: Complete Developer Guide

Validating JSON data is crucial for building reliable applications. This guide covers everything about JSON validation via API, including common validation errors, error handling, and implementation examples in multiple programming languages.

What is JSON Validation?

JSON validation verifies that a string conforms to the JSON specification (RFC 8259). This includes checking for proper syntax, correct data types, and valid structure. Invalid JSON will cause parsing errors in applications.

Valid JSON example: {"name": "John", "age": 30}

Common JSON Errors

Understanding common JSON syntax errors helps in debugging:

Trailing Commas

JSON doesn't allow trailing commas. {"a": 1,} is invalid.

Single Quotes

JSON requires double quotes. {'name': 'John'} is invalid.

Unquoted Keys

Object keys must be strings. {name: "John"} is invalid.

Using the JSON Validator API

TinyFn provides a simple endpoint to validate JSON:

POST https://api.tinyfn.io/v1/validate/json
Headers: X-API-Key: your-api-key
Content-Type: application/json

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

{
  "valid": true,
  "parsed": {
    "name": "John",
    "age": 30
  }
}

{
  "valid": false,
  "error": {
    "message": "Unexpected token } at position 15",
    "line": 1,
    "column": 15
  }
}

Parameters

Code Examples

JavaScript / Node.js

const jsonString = '{"name": "John", "age": 30}';
const response = await fetch(
  'https://api.tinyfn.io/v1/validate/json',
  {
    method: 'POST',
    headers: {
      'X-API-Key': 'your-api-key',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ json: jsonString })
  }
);
const result = await response.json();
console.log(result.valid); // true

Python

import requests

json_string = '{"name": "John", "age": 30}'
response = requests.post(
    'https://api.tinyfn.io/v1/validate/json',
    headers={'X-API-Key': 'your-api-key'},
    json={'json': json_string}
)
result = response.json()
print(result['valid'])  # True

cURL

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

Common Use Cases

• API Input Validation: Validate JSON payloads before processing
• Config File Checking: Verify JSON configuration files are valid
• Form Validation: Check user-submitted JSON in web forms
• Data Import: Validate JSON before importing into databases
• CI/CD Pipelines: Validate JSON files in build processes

Best Practices

1. Validate early: Check JSON validity before processing to fail fast
2. Handle errors gracefully: Provide helpful error messages to users
3. Consider schema validation: Use JSON Schema for structural validation
4. Escape properly: Ensure special characters are escaped in JSON strings