IPv4 to IPv6 Mapping API: The Complete Guide

Need to represent IPv4 addresses in IPv6 format? This guide covers everything about IPv4-to-IPv6 mapping via API, including mapping types, dual-stack networking, and implementation examples.

What is IPv4 to IPv6 Mapping?

IPv4-mapped IPv6 addresses allow IPv4 addresses to be represented in IPv6 format. This is essential for dual-stack systems that need to handle both protocols seamlessly.

For example, 192.168.1.1 becomes ::ffff:192.168.1.1 or ::ffff:c0a8:0101 in IPv6 format.

Mapping Types

IPv4-Mapped IPv6 Address

Format: ::ffff:IPv4

Used for communication between IPv6-only hosts and IPv4 hosts.

• ::ffff:192.168.1.1 (mixed notation)
• ::ffff:c0a8:0101 (full hex notation)

IPv4-Compatible IPv6 Address (Deprecated)

Format: ::IPv4

Older format, now deprecated in favor of mapped addresses.

Using the IPv4 to IPv6 API

TinyFn provides an endpoint for IPv4 to IPv6 mapping:

GET https://api.tinyfn.io/v1/ip/ipv4-to-ipv6?ip=192.168.1.1
Headers: X-API-Key: your-api-key

{
  "ipv4": "192.168.1.1",
  "ipv6_mapped": "::ffff:192.168.1.1",
  "ipv6_mapped_full": "::ffff:c0a8:0101",
  "ipv6_expanded": "0000:0000:0000:0000:0000:ffff:c0a8:0101",
  "ipv6_compatible": "::192.168.1.1"
}

Parameters

Code Examples

JavaScript / Node.js

const response = await fetch(
  'https://api.tinyfn.io/v1/ip/ipv4-to-ipv6?ip=192.168.1.1',
  { headers: { 'X-API-Key': 'your-api-key' } }
);
const { ipv6_mapped } = await response.json();
console.log(ipv6_mapped); // "::ffff:192.168.1.1"

Python

import requests

response = requests.get(
    'https://api.tinyfn.io/v1/ip/ipv4-to-ipv6',
    headers={'X-API-Key': 'your-api-key'},
    params={'ip': '192.168.1.1'}
)
ipv6 = response.json()['ipv6_mapped']
print(ipv6)  # "::ffff:192.168.1.1"

cURL

curl "https://api.tinyfn.io/v1/ip/ipv4-to-ipv6?ip=192.168.1.1" \
  -H "X-API-Key: your-api-key"

Common Use Cases

• Dual-Stack Applications: Support both IPv4 and IPv6 in single codebase
• Socket Programming: Use IPv6 sockets that accept IPv4 connections
• Database Storage: Store all IPs in unified IPv6 format
• Migration Planning: Prepare for IPv4 to IPv6 transition
• Logging Standardization: Consistent IP format in logs

Best Practices

1. Use mapped format: ::ffff: prefix is the standard for dual-stack
2. Store in IPv6 format: Modern systems should use IPv6-native storage
3. Display appropriately: Show mixed notation for human readability
4. Handle both formats: Accept both IPv4 and IPv6 inputs in your applications

Use via MCP

Your AI agent can call this tool directly via Model Context Protocol — no HTTP code needed. Add TinyFn to Claude Desktop, Cursor, or any MCP client:

{
  "mcpServers": {
    "tinyfn-ip": {
      "url": "https://api.tinyfn.io/mcp/ip/",
      "headers": {
        "X-API-Key": "your-api-key"
      }
    }
  }
}

See all ip address tools available via MCP in our IP Address MCP Tools for AI Agents guide.