Headers and JSON Body

Master the art of converting cURL commands with authentication headers, JSON request bodies, and nested data structures.

Authentication Headers

Bearer Token (Most Common)

curl https://api.example.com/data \
  -H "Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."

Converts to Python:

import requests

url = "https://api.example.com/data"
headers = {
    "Authorization": "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
}

response = requests.get(url, headers=headers)

API Key Header

curl https://api.example.com/data \
  -H "X-API-Key: your_api_key_here"

JSON Request Bodies

Simple JSON POST

curl -X POST https://api.example.com/users \
  -H "Content-Type: application/json" \
  -d '{"name":"John Doe","email":"[email protected]","age":30}'

Converts to Python:

import requests

url = "https://api.example.com/users"
headers = {
    "Content-Type": "application/json"
}
data = {
    "name": "John Doe",
    "email": "[email protected]",
    "age": 30
}

response = requests.post(url, headers=headers, json=data)

JavaScript (Fetch):

fetch('https://api.example.com/users', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'John Doe',
    email: '[email protected]',
    age: 30
  })
})
  .then(response => response.json())
  .then(data => console.log(data));

Bearer Token + JSON Body

curl -X GET https://api.example.com/user/profile \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json"

Converts to Python:

import requests

url = "https://api.example.com/user/profile"
headers = {
    "Authorization": "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...",
    "Content-Type": "application/json"
}

response = requests.get(url, headers=headers)

API Key in Header

curl -X GET https://api.example.com/data \
  -H "X-API-Key: YOUR_API_KEY_HERE"

Converts to Node.js (Axios):

const axios = require('axios');

axios.get('https://api.example.com/data', {
  headers: {
    'X-API-Key': 'YOUR_API_KEY_HERE'
  }
})
  .then(response => console.log(response.data));

Nested JSON Objects

curl -X POST https://api.example.com/orders \
  -H "Content-Type: application/json" \
  -d '{
    "order_id": "ORD-123",
    "customer": {
      "name": "John Doe",
      "email": "[email protected]"
    },
    "items": [
      {"product_id": "P1", "quantity": 2},
      {"product_id": "P2", "quantity": 1}
    ]
  }'

Content-Type Headers

JSON (Most Common)

curl https://api.example.com/data \
  -H "Content-Type: application/json"

Form Data

curl https://api.example.com/submit \
  -H "Content-Type: application/x-www-form-urlencoded"

GraphQL

curl -X POST https://api.example.com/graphql \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -d '{"query":"{ user(id: 1) { name email } }"}'

Common Mistakes

Wrong Quote Usage

# ❌ Wrong - Shell interprets the quotes
curl -X POST https://api.example.com/data -d '{"key":"value"}'
  -H "Content-Type: application/json"

# ✅ Correct - Headers before data
curl -X POST https://api.example.com/data \
  -H "Content-Type: application/json" \
  -d '{"key":"value"}'

Escaping JSON in cURL

# ❌ Wrong - Shell interprets quotes
-d "{"key":"value"}"

# ✅ Correct - Single quotes preserve JSON
-d '{"key":"value"}'

Missing Content-Type

# ❌ Wrong - Server might not parse JSON
curl -X POST https://api.example.com/data \
  -d '{"key":"value"}'

# ✅ Correct - Explicit Content-Type
curl -X POST https://api.example.com/data \
  -H "Content-Type: application/json" \
  -d '{"key":"value"}'

Debugging Tips

1. Use RequestBin - Send requests to a RequestBin URL to inspect headers and body
2. Check quotes - Always use single quotes for JSON data in cURL
3. Validate JSON - Ensure JSON is valid before converting
4. Test incrementally - Start with simple requests, then add complexity

Try It Live

Open the converter to transform your cURL commands, or use RequestBin to test with real endpoints and inspect requests.

Related docs: How It Works | Python | JavaScript