# Netmask

> VLSM planner, IPv6, offline

- Product page: https://obelisk.club/subnetmaskcalculator
- Platforms: iPhone
- Release status: live
- Last updated: 2026-07-24T08:26:48Z
- Pricing: Free (USD 0)
- Download (iPhone): https://apps.apple.com/app/id6791678289
- Publisher: Obelisk Club (https://obelisk.club) — local-first, privacy-respecting apps built in native Swift

## About

Netmask is a subnet calculator built for network engineers, sysadmins, and students who need answers in seconds, not spreadsheets. Enter an IPv4 or IPv6 address and instantly see the network address, broadcast address, usable host range, and subnet mask — broken down bit by bit in a visualizer you can tap to reshape the mask boundary by hand.

Every calculation runs fully on-device: no accounts, no network calls, no ads.

— WHAT MAKES SUBNETMASKCALCULATOR DIFFERENT —

• A VISUALIZER YOU CAN TOUCH
The binary mask view is not a diagram — tap any bit to move the boundary and watch every result re-derive live. Subnetting becomes something you feel, not something you look up.

• VLSM SPLITTER (PRO)
Give it one base block and a list of host requirements; it returns right-sized subnets in order — no gaps, no overlaps. The planning step that used to be a spreadsheet afternoon becomes a thirty-second check.

• FULL IPv6, NOT AN AFTERTHOUGHT
Compressed and expanded address forms, prefix math, total-address counts — the same clean interface handles both families.

• PRIVATE BY ARCHITECTURE
No accounts, no analytics, no network calls. Every calculation and every saved plan lives on the device only.

— PRICING —

The core IPv4 and IPv6 calculators are included in the base install. Netmask Pro — the VLSM splitter, range & aggregation tools, unlimited saved history, and CSV export — is available as a monthly subscription, an annual subscription with a 7-day trial, or a one-time lifetime unlock. No ads in any tier.

— FEEDBACK —

Made by Peter Zhang. Every email at obeliskclubclub@gmail.com is read personally.

Learn more: https://obelisk.club/subnetmaskcalculator

Terms of Use (EULA): https://obelisk.club/subnetmaskcalculator/terms

## Key features

- **Instant IPv4 & IPv6 subnet calculator**
- **Tap-to-toggle binary mask visualizer**
- **VLSM subnet splitter for multi-subnet planning (Pro)**
- **Unlimited history & CSV export (Pro)**
- **One-tap copy or share for every result field**
- **Fully offline — no accounts, no tracking**