Expand CIDR Range API: The Complete Guide

Need to list all IP addresses in a network range? This guide covers everything about expanding CIDR notation via API, including handling large ranges, pagination, and implementation examples.

What is CIDR Expansion?

CIDR expansion converts a compact network notation like 192.168.1.0/24 into a complete list of all IP addresses in that range. A /24 network contains 256 addresses (from .0 to .255).

This is useful for scanning, inventory, whitelisting, and other operations that need explicit IP addresses.

Handling Large Ranges

Network sizes vary dramatically:

• /32 = 1 IP
• /24 = 256 IPs
• /16 = 65,536 IPs
• /8 = 16,777,216 IPs

Using the Expand CIDR API

TinyFn provides an endpoint for CIDR expansion with pagination:

GET https://api.tinyfn.io/v1/ip/expand-cidr?cidr=192.168.1.0/28
Headers: X-API-Key: your-api-key

{
  "cidr": "192.168.1.0/28",
  "total_addresses": 16,
  "ips": [
    "192.168.1.0",
    "192.168.1.1",
    "192.168.1.2",
    "192.168.1.3",
    "192.168.1.4",
    "192.168.1.5",
    "192.168.1.6",
    "192.168.1.7",
    "192.168.1.8",
    "192.168.1.9",
    "192.168.1.10",
    "192.168.1.11",
    "192.168.1.12",
    "192.168.1.13",
    "192.168.1.14",
    "192.168.1.15"
  ],
  "first_ip": "192.168.1.0",
  "last_ip": "192.168.1.15"
}

Parameters

Code Examples

JavaScript / Node.js

const response = await fetch(
  'https://api.tinyfn.io/v1/ip/expand-cidr?cidr=192.168.1.0/28',
  { headers: { 'X-API-Key': 'your-api-key' } }
);
const { ips, total_addresses } = await response.json();
console.log(`Total: ${total_addresses} IPs`);
ips.forEach(ip => console.log(ip));

Python

import requests

response = requests.get(
    'https://api.tinyfn.io/v1/ip/expand-cidr',
    headers={'X-API-Key': 'your-api-key'},
    params={'cidr': '192.168.1.0/28'}
)
data = response.json()
print(f"Total: {data['total_addresses']} IPs")
for ip in data['ips']:
    print(ip)

cURL

curl "https://api.tinyfn.io/v1/ip/expand-cidr?cidr=192.168.1.0/28" \
  -H "X-API-Key: your-api-key"

Common Use Cases

• Network Scanning: Generate target list for security scans
• IP Whitelisting: Populate firewall rules from CIDR notation
• Inventory Management: Track all IPs in allocated ranges
• DNS Configuration: Generate reverse DNS entries
• Monitoring Setup: Configure monitoring for all network hosts

Best Practices

1. Use pagination: Process large ranges in chunks to manage memory
2. Exclude special addresses: Often network and broadcast aren't needed
3. Validate CIDR first: Ensure the CIDR is valid before expansion
4. Consider alternatives: For very large ranges, iterate mathematically instead

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.