SubnetBuddy

SubnetBuddy is a fast, offline subnet calculator and network planning tool built for IT professionals, network engineers, students, and anyone studying for their CCNA, CompTIA Network+, or just needs to crunch CIDR notation on the fly.

No internet required. No ads. No account needed. Just open the app and start calculating.

SUBNET CALCULATOR • Enter any IP address and CIDR prefix (e.g. 192.168.1.0/24) • Instantly see network address, broadcast address, first and last usable host • View total hosts, usable hosts, and wildcard mask • Get the next sequential subnet with one tap • Supports all prefix lengths from /0 to /32

MASK CONVERTER • Convert between CIDR notation, dotted decimal, and binary • Enter a prefix length and see all three formats instantly • Quick-reference for common subnet masks • Perfect for exam prep and on-the-job lookups

VLAN PLANNER • Plan multiple VLANs with custom names and sizes • Set a base network and SubnetBuddy calculates non-overlapping subnets for each VLAN • See network range, gateway, CIDR, and host count per VLAN • Great for designing office networks, lab environments, and homework assignments

IP VISUALIZER • Enter a CIDR block and see a visual map of the IP address space • Color-coded grid shows used vs. available addresses • Instantly understand how big (or small) your subnet really is • Tap any cell to see the full IP address

TERMINAL-STYLE DESIGN • Dark theme with VibeCMD's signature hacker-green aesthetic • Monospace fonts and command-line inspired interface • Clean, distraction-free layout built for speed • Easy on the eyes during late-night study sessions

WORKS COMPLETELY OFFLINE • Zero network calls — all calculations happen on-device • No account required — open and use immediately • No data collection — your network plans stay on your phone • Lightning fast — results appear as you type

BUILT FOR REAL PEOPLE • IT professionals doing quick subnet math on-site • Students studying for CCNA, Network+, or any networking exam • Homelab enthusiasts planning their network segments • DevOps engineers carving up VPC address spaces • Anyone who's tired of Googling "what is /22 in dotted decimal"

SubnetBuddy is a utility tool for network address calculations. It does not connect to or scan any networks.