KEEPING A CAT indoors is the only surefire way to know where it is at all times. But if you’ve got an outdoor feline, there’s a digital way to keep tabs on it.

Companies like Fi, Jiobit and Tractive sell cat trackers. They clip onto a collar or harness, sync up to your phone over cellular signals and cost about $50 (with an annual subscription of $100 to $190 per year).

In addition to sending live location data, some trackers offer:

• Physical activity and sleep info.

• Alerts if your cat wanders outside a geographic area you determine.

• Daily reports. Learn where your cat goes. “Tons of cat owners discover: Surprise! My cat has another family they visit every day,” says Andrew Bleiman, an executive vice president at Tractive. —Claire Leibowitz