Free, lawful options exist, but each one requires the other person to opt in — that is the price of free, and it is also why they work reliably.
What is genuinely free:
- Apple Find My — free, precise on iPhone, requires Family Sharing and Share My Location. People-tab location updates roughly every few minutes; it is the best free option on iOS.
- Google Maps location sharing — free on Android and iPhone, the other person picks the duration (1 hour to until turned off). History can be visible if they enable it.
- Google Family Link — free, for a child's supervised Google account. Location, app blocking, screen time, and it notifies the child.
- Life360 free tier — free circles, decent accuracy, but it upsells heavily and the free plan has lost features over time.
- Carrier family apps — not free, but if the line is already on your account, Verizon/AT&T/T-Mobile bundles often include a basic locator at no extra cost.
What free will not do: read messages, see call logs, or run without the other person knowing. Those capabilities require an installed app with device-level permissions, which means a one-time physical setup on a device you own.
That is where a paid product fits — Ultimate Phone Spy covers Android, Windows and Mac for location history, geofences, messages and calls under one dashboard (plans from $16/month). If all you need is "where is my teenager right now", Find My or Family Link is free and better than any paid app; the paid tools earn their keep when you need context, not just a pin.