Network Engineering Tools

Free, fast, and accurate tools for subnet calculation, IP planning, VLAN management, and network configuration generation. No account needed.

No signup · Runs in your browser · Used by CCNA/JNCIA candidates

Quick Subnet Calculator

Enter a CIDR block to see the network address, broadcast address, and usable host count.

Try it out, or use the full Subnet Calculator for detailed results.

Start Here

Subnet Calculator

Calculate network address, broadcast, host range, and more from any IPv4/IPv6 CIDR.

IP Planner

Plan subnets based on device counts per segment with growth margin.

Learning Hub

Interactive tutorials and courses to master subnetting, CIDR, and networking fundamentals.

Subnetting Cheat Sheet

Quick reference tables for CIDR prefixes, subnet masks, and host counts.

Subnet & IP Calculators

Subnet Calculator

Calculate network address, broadcast, host range, and more from any IPv4/IPv6 CIDR.

IPv4 Subnet Calculator

Classful and classless IPv4 subnetting with full breakdown.

IPv6 Subnet Calculator

Expand, shorten, and analyze IPv6 addresses and prefixes.

Wildcard Mask Calculator

Convert CIDR to wildcard masks for ACL configurations.

Binary Converter

Convert IP addresses between binary, hex, and decimal formats.

Supernet Calculator

Aggregate multiple CIDR blocks into the smallest supernet.

Overlap Detector

Check multiple CIDR ranges for IP address collisions.

Subnet Splitter

Split any CIDR block into equal-sized subnets for network planning.

Bandwidth Calculator

Calculate throughput, transfer times, and compare link types.

Planning & Design

IP Planner

Plan subnets based on device counts per segment with growth margin.

VLAN Planner

Plan VLAN IDs with subnet assignments and descriptions.

Cloud IP Planner

Design VPC subnets for AWS, Azure, and GCP across availability zones.

VPC Peering Check

Verify non-overlapping CIDRs before establishing VPC peering connections.

Transit Gateway Planner

Design AWS Transit Gateway topologies with route tables and overlap detection.

Automation & Configuration

Config Generator

Generate router/switch configs for Cisco, Juniper, Huawei, Arista, and more.

BGP Prefix Filter Builder

Generate Cisco and Juniper prefix-list and route-map configurations.

Diagnostics & Lookup

DNS Lookup

Look up A, AAAA, MX, NS, CNAME, TXT, and other DNS records.

MAC Address Lookup

Look up OUI vendor, identify MAC type, and convert to EUI-64.

SSL/TLS Checker

Inspect SSL/TLS certificate details, expiry dates, and SANs for any domain.

Port Scanner

Check which TCP ports are open on any host with service identification.

Learn & Practice

Learning Hub

Interactive tutorials and courses to master subnetting, CIDR, and networking fundamentals.

Subnetting Cheat Sheet

Quick reference tables for CIDR prefixes, subnet masks, and host counts.

Subnetting Quiz

Test your subnetting skills with interactive practice questions.

Subnet Randomizer

Generate random subnetting questions to practice your skills.

Why NetworkTools?

NetworkTools is a comprehensive suite of free online tools designed for network engineers, system administrators, and IT students. Whether you are calculating subnets for a new deployment, planning IP allocations across multiple segments, designing VLANs for your campus network, or preparing for certification exams like CCNA or JNCIA, NetworkTools provides accurate results instantly.

Unlike traditional IP address management (IPAM) solutions that require installation, configuration, and ongoing maintenance, NetworkTools runs entirely in your browser. Every tool is a standalone page with its own URL, making it easy to bookmark, share, and reference later. There is no login required, no software to install, and no data leaves your browser for core calculations.

Our tools support the full spectrum of network engineering tasks: from basic binary conversion and wildcard mask calculation to advanced multi-region cloud IP planning and vendor-specific configuration generation. We support Cisco IOS, Juniper JunOS, Huawei VRP, Arista EOS, MikroTik RouterOS, and Fortinet FortiOS — with Terraform export for infrastructure-as-code workflows.

Accuracy is the point of these tools. Every subnet calculation follows the RFC 1918 private addressing ranges and RFC 3021 point-to-point rules for /31 links, and the arithmetic is implemented as pure client-side functions rather than opaque server calls. That means you can trace exactly how a network address, broadcast address, or usable host count was derived, and verify it against your own working. Nothing is sent to a backend for the core math, so results appear instantly, even on a slow connection, and remain consistent whether you are on a laptop, a tablet, or a lab machine.

NetworkTools is built for the people who actually operate networks: network engineers designing address plans, sysadmins carving up a single /24 for a branch office, students learning binary math for the first time, and cloud architects mapping subnets across VPCs, availability zones, and Transit Gateways. When a design is ready to implement, the configuration generator turns it into ready-to-paste vendor configuration for Cisco IOS, Juniper JunOS, Huawei VRP, Arista EOS, MikroTik RouterOS, and Fortinet FortiOS, plus Terraform for infrastructure-as-code pipelines.