SubnetDeck: Subnet Calculator

Offline IP Planner, VLSM, CIDR

Free · In‑App Purchases · Designed for iPad. Not verified for macOS.

No signal in the server room? SubnetDeck never goes online. The calculator and lessons are free; Premium adds 69 playbooks and IP plans for every site you manage. SubnetDeck is an offline subnet calculator and IP address planning kit for network engineers and IT staff. It never connects to the internet, so it keeps working in server rooms, data centers, factories, closed networks and during outages. FREE • IPv4 and IPv6 calculator with a keypad that only accepts valid input (hardware keyboards supported) • Binary boundary bar that shows exactly where the network bits end • Network, broadcast, first and last address, usable hosts, wildcard mask and reverse DNS zone • /31 (RFC 3021) and /32 handled correctly; special-purpose addresses identified • 11 Learn topics: masks and prefixes, why two addresses are subtracted, five kinds of overlap, VLSM and FLSM, IPv6 and more • 13 of the 69 playbooks PREMIUM (one-time In-App Purchase, no subscription) • All 69 playbooks in 9 categories: private ranges, single sites, multi-site WAN with route aggregation, point-to-point links, segmentation, cloud networks, hybrid and migration, factory IT/OT separation, and IPv6 • Each playbook explains the reasoning, room to grow and pitfalls, and turns into a design plan with one tap • Design tab: segments by host count or prefix length, automatic VLSM allocation, overlap and issue detection • Folders for each site, customer or company, so every network's addressing stays on your device • Search plans by address: which plan contains 10.1.2.3, and which overlaps a block • Tools: equal split (FLSM), route summarization and overlap check • Export to Markdown, CSV and .xlsx; export and import all plans when you change devices • Reserved-address deduction profiles for cloud subnets • Optional inclusion of your plans in iCloud Backup PRIVATE BY DESIGN • No network connections, no ads, no analytics, no account • Plans are stored only on your device with file protection and are excluded from backups unless you choose otherwise • The app switcher preview hides your plans For iPhone, iPad, Mac and Apple Vision Pro. Fully localized in 9 languages: English, Japanese, Spanish, German, French, Portuguese (Brazil), Chinese (Simplified and Traditional) and Korean.

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The developer, Yoshihiko Ishikawa, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

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    Information

    Seller
    Yoshihiko Ishikawa
    Size
    7.9 MB
    Category
    Reference
    Compatibility
    Requires iOS 18.0 or later.
    • iPhone
      Requires iOS 18.0 or later.
    • iPad
      Requires iPadOS 18.0 or later.
    • Mac
      Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 2.0 or later.
    Languages
    English and 8 more
    • English, French, German, Japanese, Korean, Portuguese, Simplified Chinese, Spanish, Traditional Chinese
    Age Rating
    4+
    In-App Purchases
    Yes
    Copyright
    © 2026 Okojyo-Soft
  • Developer Website
  • Privacy Policy

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