Tethra: Signal & Dead Zone Map

Cell coverage & no-data alerts

Only for iPhone

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

iPhone

Know exactly where your mobile data works — and where it doesn't. Map your own coverage, get warned before dead zones, and keep mapping even with no signal. Ever lost signal just when you needed to send a message? Tethra shows you exactly where your phone has mobile data — on your commute, on the road, on the trail. Tethra shows you where mobile data really works. It doesn't guess or borrow other people's coverage maps. It tests your connection right where you are and turns every check into your own personal coverage map, one hexagon at a time. Tethra gives you the facts and leaves the decisions to you. Each result is a snapshot of one place at one moment, and networks change, so your map grows more useful the more you explore. YOUR OWN COVERAGE MAP • Every check colours a hexagon: Strong, Fair, Weak or No signal • No signal is drawn hatched, so dead zones stand out at a glance • Each hexagon shows its latest result, how fast data responded and your history there • Filter by all time, the last 30 days, or dead zones only • Street map or satellite view MAPS IN THE BACKGROUND With location set to Always, Tethra checks as you go about your day — no need to open the app. Your map grows on its own. TRIPS • Start a trip for a dense map along your route: a check every 50, 100 or 250 metres • Get an alert the moment signal is lost, and another when it's back • Tethra keeps mapping even without signal, so you see exactly where it ends • The last place with signal is marked on the map • Follow your trip on the Lock Screen and in the Dynamic Island • Every trip gets a summary: coverage along the route, longest dead zone, how often signal was lost WARNINGS BEFORE DEAD ZONES Tethra remembers where you lost signal before and warns you as you approach — send that important message first. SAVED SPOTS & SEARCH Save the places that matter and search for any address to see your coverage there. PRIVATE BY DESIGN • No account, no sign-up, no ads • Your map and trips are stored on your iPhone • Each check only opens a secure connection to test mobile data — nothing is sent Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://radulysandor.github.io

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

  • Data Not Collected

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    Accessibility

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    Information

    Seller
    Raduly Sandor
    Size
    6.3 MB
    Category
    Navigation
    Compatibility
    Requires iOS 26.0 or later.
    • iPhone
      Requires iOS 26.0 or later.
    • Mac
      Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 26.0 or later.
    Location
    This app may use your location even when it isn’t open, which can decrease device battery life.
    Languages
    English
    Age Rating
    9+
    In-App Purchases
    Yes
    • Tethra Premium $9.99
    • Tethra Lifetime $19.99
    • Tethra Premium $1.99
    • Learn More
    Copyright
    © Ráduly Sándor
  • Privacy Policy

    • More by Raduly Sandor