Everything you need to know

A normal alarm fires at a clock time you set in advance, which means guessing how long your journey will take. A GPS alarm ignores the clock and watches your position instead, sounding when you come within a distance you chose of your destination. A delay makes the journey longer; it doesn't move the destination — which is why a location alarm suits public transport and a clock alarm doesn't.

Yes — free to download, with optional Pro features. The core location alarm, Subway Watchdog, Trip Buddy and the Anti-Theft Shield are all in the free, ad-supported app. Gentle Wake, Smart Reminders and trip history sit in the Pro tier, which you can unlock with Z-Coins earned by watching ads or buy outright as a one-time Lifetime Pro purchase that also removes the ads.

Nap Alarm is on the Google Play Store, for Android devices. It isn't tied to a particular city or transit operator — you set your own destination, so it works on whatever route you travel. There is no iOS version yet.

Open the app, search for your destination station or bus stop, set a proximity buffer (e.g. wake me 500m before I arrive), then lock your phone and sleep. Nap Alarm runs a native background service that continuously checks your position and fires the alarm when you enter the buffer zone — no internet required after the route is set.

Yes, and you should — being woken at your stop means standing up in a hurry. You can set a custom proximity buffer anywhere from 200 m to 5 km, shown in kilometres, metres, miles or feet depending on the units you pick. There is also a time-based mode that wakes you a set number of minutes before your projected arrival, recalculated as delays change.

Yes. Tracking runs in an Android foreground service, which operates independently of the screen state and survives the app being swiped out of recents, so the alarm still fires with the screen off and the phone locked. One thing worth knowing: some Android manufacturers apply their own aggressive battery restrictions on top of stock Android. If your device does that, exempting Nap Alarm from battery optimisation in your system settings is the reliable fix.

Any app that tracks your position continuously uses some battery — there is no way around that. Nap Alarm is built to keep it down: the background location worker uses Doze-aware scheduling and paces its GPS polling against your travel speed and remaining distance, rather than polling at a fixed high rate for the whole journey. Actual drain depends on your device, your route length, and how strong the GPS signal is.

This is the feature Nap Alarm is built around. After two continuous minutes without a GPS fix — typically when you enter a tunnel — Subway Watchdog activates on its own and switches to predictive tracking rather than waiting for the signal to return, using your saved route and its average stop intervals to keep advancing an estimate of where you are. It hands back to live GPS the moment the train resurfaces. Because it is an estimate and not a measurement, delays, long dwell times and diversions all push it off, so a wider buffer gives it room to be slightly early rather than slightly late.

Subway Watchdog isn't tied to a particular city or operator — it keys off GPS availability, so it applies on any underground system where the signal drops, including those three. Because the prediction is built from your own saved route and stop timings, it has more to work from on a line you travel regularly than on one you're riding for the first time.

Trip Buddy pairs you with someone you trust using a six-digit code you generate in the app, in one-way or two-way mode. It arms itself only during an active trip: if the arrival alarm sounds at your destination and nobody stops it within the expected window, the app treats you as unresponsive and alerts your buddy with your live location and a one-tap call button, playing a siren that is designed to cut through Do Not Disturb. Stopping the alarm deletes the emergency and mutes their siren straight away.

No. Pairing does not grant ongoing tracking. Your location is shared only when both conditions are true — you have an active trip and the emergency has been triggered — and it stops as soon as you stop the alarm. Worth knowing that Trip Buddy alerts the person you paired with, not the emergency services, and getting the alert through depends on both phones having a connection and on your buddy having notifications enabled.

Arm the Anti-Theft Shield before you sleep and the app watches for the signs of your phone being taken — unplugged from its charger, moved sharply, or picked up. It sounds an immediate, distinct alarm without waiting for your location alarm to be due.