Is the NetTools API free to use?

Yes. The NetTools API is completely free with no authentication or API key required. Rate limits are applied per IP address: 60 requests per minute for computation endpoints and 30 per minute for proxy endpoints.

API Documentation

Q: What happens when I exceed the rate limit?

You receive a 429 Too Many Requests response with a Retry-After header indicating how many seconds to wait. The X-RateLimit-Reset header on every response tells you when your window resets.

Free REST API for network calculations. JSON responses, no authentication required.

Overview

Base URLhttps://nettools.zybergen.com/apiFormatJSONAuthNone requiredRate Limits30–60 requests/minute per IP per endpoint

Response Format

All endpoints return a consistent JSON envelope:

Success

{ "success": true, "data": { ... } }

Error

{ "success": false, "error": "..." }

Rate limit headers are included on every response: X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset. Exceeded limits return 429 with a Retry-After header.

Endpoints

GET/api/subnet60 req/min

Calculate IPv4 subnet details from a CIDR block.

Parameters

Name	Required	Description
cidr	Yes	CIDR notation (e.g. 10.0.0.0/24)

Example request

curl "https://nettools.zybergen.com/api/subnet?cidr=10.0.0.0/24"

Example response

{
  "success": true,
  "data": {
    "version": 4,
    "networkAddress": "10.0.0.0",
    "broadcastAddress": "10.0.0.255",
    "firstUsableIP": "10.0.0.1",
    "lastUsableIP": "10.0.0.254",
    "totalHosts": 256,
    "usableHosts": 254,
    "subnetMask": "255.255.255.0",
    "cidr": 24,
    "ipClass": "A"
  }
}

GET/api/vlsm60 req/min

Allocate variable-length subnets within a parent CIDR block.

Parameters

Name	Required	Description
parent	Yes	Parent CIDR (e.g. 10.0.0.0/16)
subnets	Yes	Comma-separated Name:HostCount pairs (e.g. Servers:500,Users:200)

Example request

curl "https://nettools.zybergen.com/api/vlsm?parent=10.0.0.0/16&subnets=Servers:500,Users:200,IoT:50"

Example response

{
  "success": true,
  "data": {
    "parentNetwork": "10.0.0.0",
    "parentCidr": 16,
    "totalAddresses": 65536,
    "allocatedAddresses": 1536,
    "allocations": [
      {
        "name": "Servers",
        "networkAddress": "10.0.0.0",
        "cidr": 22,
        "subnetMask": "255.255.252.0",
        "allocatedHosts": 1022,
        "requestedHosts": 500,
        "utilization": 49
      }
    ],
    "unallocated": [...]
  }
}

GET/api/supernet60 req/min

Aggregate a list of prefixes into summary routes.

Parameters

Name	Required	Description
prefixes	Yes	Comma-separated CIDR prefixes (e.g. 192.168.0.0/24,192.168.1.0/24)

Example request

curl "https://nettools.zybergen.com/api/supernet?prefixes=192.168.0.0/24,192.168.1.0/24"

Example response

{
  "success": true,
  "data": {
    "originalCount": 2,
    "summarizedCount": 1,
    "reductionPercent": 50,
    "original": [
      { "network": "192.168.0.0", "cidr": 24 },
      { "network": "192.168.1.0", "cidr": 24 }
    ],
    "summarized": [
      { "network": "192.168.0.0", "cidr": 23 }
    ]
  }
}

GET/api/dns30 req/min

Query DNS records for a domain via Google Public DNS.

Parameters

Name	Required	Description
name	Yes	Domain name (e.g. example.com)
type	No	Record type: A, AAAA, CNAME, MX, NS, TXT, SOA, SRV, CAA, PTR (default: A)

Example request

curl "https://nettools.zybergen.com/api/dns?name=example.com&type=MX"

Example response

{
  "success": true,
  "data": {
    "name": "example.com",
    "type": "MX",
    "status": 0,
    "dnssecValidated": true,
    "records": [
      { "name": "example.com.", "type": 15, "TTL": 3600, "data": "10 mail.example.com." }
    ]
  }
}

GET/api/whois30 req/min

Get IP geolocation, ISP, and ASN information.

Parameters

Name	Required	Description
ip	Yes	IPv4 or IPv6 address (e.g. 8.8.8.8)

Example request

curl "https://nettools.zybergen.com/api/whois?ip=8.8.8.8"

Example response

{
  "success": true,
  "data": {
    "ip": "8.8.8.8",
    "type": "v4",
    "country": "United States",
    "city": "Mountain View",
    "connection": {
      "asn": 15169,
      "org": "Google LLC",
      "isp": "Google LLC"
    }
  }
}

GET/api/myip60 req/min

Returns the requesting client's public IP address.

Example request

curl "https://nettools.zybergen.com/api/myip"

Example response

{
  "success": true,
  "data": {
    "ip": "203.0.113.42",
    "headers": {
      "x-forwarded-for": "203.0.113.42",
      "x-real-ip": null
    }
  }
}

GET/api/maclookup30 req/min

Look up the vendor/manufacturer for a MAC address (OUI lookup).

Parameters

Name	Required	Description
mac	Yes	MAC address in any format (e.g. AA:BB:CC:DD:EE:FF)

Example request

curl "https://nettools.zybergen.com/api/maclookup?mac=00:1A:2B:3C:4D:5E"

Example response

[
  {
    "startHex": "001A2B000000",
    "endHex": "001A2BFFFFFF",
    "company": "Ayecom Technology Co., Ltd.",
    "addressL1": "...",
    "country": "TW"
  }
]

GET/api/config60 req/min

Generate router/firewall interface configuration snippets.

Parameters

Name	Required	Description
cidr	Yes	Subnet in CIDR notation (e.g. 10.0.0.0/24)
interface	No	Interface name (default: GigabitEthernet0/1)
vendor	No	Filter to one vendor: cisco-ios, junos, fortios (default: all)
description	No	Interface description

Example request

curl "https://nettools.zybergen.com/api/config?cidr=10.0.0.0/24&interface=ge-0/0/0&vendor=junos"

Example response

{
  "success": true,
  "data": {
    "network": "10.0.0.0",
    "cidr": 24,
    "subnetMask": "255.255.255.0",
    "interfaceName": "ge-0/0/0",
    "configs": {
      "junos": "set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.1/24\n..."
    }
  }
}

About the NetTools API

The NetTools REST API provides programmatic access to all network calculation tools available on this site. Every endpoint returns JSON and requires no authentication, making it easy to integrate into scripts, CI/CD pipelines, network automation workflows, and custom dashboards.

Use the API to automate subnet calculations during infrastructure provisioning, validate DNS records as part of deployment checks, or generate router configurations from your IP address management (IPAM) system. All computation endpoints run server-side with no external dependencies, ensuring fast and reliable responses.

Frequently Asked Questions

Is the API free to use?

Yes. The NetTools API is completely free with no authentication or API key required. Rate limits are applied per IP address to ensure fair usage — computation endpoints allow 60 requests per minute and proxy endpoints (DNS, Whois, MAC lookup) allow 30 requests per minute.

What happens when I exceed the rate limit?

You will receive a 429 (Too Many Requests) response with a Retry-After header indicating how many seconds to wait before making another request. The X-RateLimit-Reset header on every response tells you when your rate limit window resets (Unix timestamp).

Can I use the API in commercial projects?

Yes. The API is available for both personal and commercial use. However, please respect the rate limits and avoid using it as a critical dependency for high-traffic production systems without reaching out first. For heavy usage, consider running the computation functions locally — they are pure math with no external dependencies.

Do I need CORS headers for browser-side requests?

The API endpoints are designed primarily for server-side usage (scripts, backends, CLI tools). For browser-based applications making cross-origin requests, you may need to proxy the requests through your own backend. Direct browser requests from the same domain (nettools.zybergen.com) work without CORS issues.