NetEng Sidekick: Subnet Calculator

About

NetEng Sidekick - Offline Subnet Calculator
🛑 Stop switching tabs during critical maintenance windows.
🖥️ Created by a network engineer for network engineers.

NetEng Sidekick is the workflow accelerator designed specifically for Wired and Wireless Network Engineers, Sysadmins, and Cloud Architects. It moves the subnet calculator from a browser tab to a permanent Side Panel—keeping your calculations visible while you configure Wireless LAN Controllers, audit Firewall ACLs, or design Cloud VPCs.

🚀 Why this is your new favorite tool:

1. Always-On Side Panel 🖥️ Never lose your place again. Whether you are scrolling through a Cisco CLI session in a browser terminal or reading Azure documentation, your calculator stays open and ready on the right side of your screen.

2. Serious IPv6 Power 🌐 IPv6 isn't the future; it's the now. While other calculators fail at 128-bit math, NetEng Sidekick handles full IPv6 precision.

Calculate Prefix Delegations for ISP handoffs.

Visualize /64 breakdowns for IoT VLANs.

Get accurate Range Start/End for massive address blocks without crashing your browser.

3. Smart Input (Cisco & Legacy Friendly) 🧠 We know the real world isn't always CIDR.

Paste standard CIDR: 192.168.10.1/24

Paste legacy masks: 192.168.10.1 255.255.255.0 We handle both automatically. No toggles required.

4. Visual VLSM Breakdown 🍰 Need to carve up a /24 Management VLAN into smaller chunks for different building wings?

Select your new mask size (e.g., /27).

Instantly see a table of every available subnet.

Click to copy the Network ID or Broadcast address instantly.

5. One-Click Efficiency ⚡ Every result is clickable. Copy the First Usable IP for your Gateway configuration or the Wildcard Mask for your OSPF config with a single click.

6. Export for Documentation 📄 [NEW] Done with your design? Export your calculation results to a .txt file instantly. Perfect for attaching to Change Management requests, Jira tickets, or saving to your project documentation folder.

🛠️ Built for the Daily Life of a Network Engineer

WIRELESS ENGINEERS: Quickly calculate subnet sizes for Guest WiFi pools to ensure you don't run out of DHCP leases during peak hours. Verify AP Management subnets when deploying new controllers.

WIRED ENGINEERS: Rapidly verify if a specific IP falls inside a Summary Route or ACL object group without leaving your monitoring dashboard.

SECURITY TEAMS: Double-check CIDR ranges when whitelisting IP blocks in your WAF or Firewall to prevent accidental over-exposure.

NETWORK ARCHITECTS: Plan complex VLSM schemas and export the plan to text files to share with the implementation team.

🔒 Privacy First

100% Client-Side: No data ever leaves your browser.

Offline Ready: Works perfectly in air-gapped environments or when the internet is down (which is usually when you need it most!).

Upgrade your workflow today. Add NetEng Sidekick to Chrome.