CIDR Calculator API: Complete Developer Guide

Need to calculate network ranges from CIDR notation? This guide covers everything about CIDR calculation via API, including subnet masks, IP ranges, and implementation examples in multiple programming languages.

What is CIDR?

CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses and routing. It uses a suffix to indicate the network portion of the address, replacing the older class-based system.

Example: 192.168.1.0/24 represents a network with 256 addresses (192.168.1.0 - 192.168.1.255)

CIDR Components

Understanding CIDR notation:

Network Address

The base IP address of the network (e.g., 192.168.1.0)

Prefix Length

The number after the slash indicates network bits. /24 means 24 network bits, 8 host bits.

Subnet Mask

/24 equals subnet mask 255.255.255.0, determining network vs host portions.

Using the CIDR Calculator API

TinyFn provides a comprehensive endpoint to calculate CIDR networks:

GET https://api.tinyfn.io/v1/network/cidr?cidr=192.168.1.0/24
Headers: X-API-Key: your-api-key

{
  "cidr": "192.168.1.0/24",
  "network_address": "192.168.1.0",
  "broadcast_address": "192.168.1.255",
  "subnet_mask": "255.255.255.0",
  "wildcard_mask": "0.0.0.255",
  "first_host": "192.168.1.1",
  "last_host": "192.168.1.254",
  "total_hosts": 256,
  "usable_hosts": 254,
  "ip_version": 4
}

Parameters

Code Examples

JavaScript / Node.js

const response = await fetch(
  'https://api.tinyfn.io/v1/network/cidr?cidr=10.0.0.0/16',
  { headers: { 'X-API-Key': 'your-api-key' } }
);
const result = await response.json();
console.log(`Range: ${result.first_host} - ${result.last_host}`);
console.log(`Usable hosts: ${result.usable_hosts}`);

Python

import requests

response = requests.get(
    'https://api.tinyfn.io/v1/network/cidr',
    params={'cidr': '10.0.0.0/16'},
    headers={'X-API-Key': 'your-api-key'}
)
result = response.json()
print(f"Range: {result['first_host']} - {result['last_host']}")
print(f"Usable hosts: {result['usable_hosts']}")

cURL

curl "https://api.tinyfn.io/v1/network/cidr?cidr=10.0.0.0/16" \
  -H "X-API-Key: your-api-key"

Common Use Cases

• Network Planning: Calculate IP ranges for network segments
• Cloud Infrastructure: Plan VPC and subnet configurations
• Firewall Rules: Define allow/deny rules with CIDR ranges
• IP Management: Track allocated and available IP addresses
• Documentation: Generate network documentation automatically

Best Practices

1. Plan for growth: Choose CIDR ranges with room for expansion
2. Avoid overlap: Ensure subnets don't overlap in your infrastructure
3. Use private ranges: Use RFC 1918 ranges (10.x, 172.16-31.x, 192.168.x) for internal networks
4. Document allocations: Keep records of CIDR allocations

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

See all network tools available via MCP in our Network MCP Tools for AI Agents guide.