If you’ve ever seen a cat slip out under a fence or watched a tiny terrier vanish into a neighbor’s yard, you know how fast “just for a minute” can turn into panic. Fi, the company best known for its smart dog collar, has tried to shrink that worry down to something you can clip onto even the most discerning feline: the new Fi Mini, a clip-on GPS tracker that’s light enough that many cats and small dogs won’t notice it’s there.

At 0.56 ounces (16 grams) and measuring roughly 42mm by 30mm, Fi says the Mini is “the lightest, smartest tracker” it has built—slightly larger than an Apple AirTag in footprint, but designed specifically to live on collars and harnesses. It clips to bands between 3/8″ and 1″ wide, so you can keep your pet’s favorite collar and still add full GPS tracking.

Physically, the Mini follows the checklist pet owners have come to expect from premium trackers: USB-C charging, an IP68 rating for dust and water resistance, and a tiny form factor that prioritizes comfort for small animals. Fi’s own product pages and early coverage emphasize that design trade-off: there’s no charging base by default (that’s optional), but you get a much smaller, collar-friendly package.

The Fi Mini uses Verizon’s LTE-M cellular network for nationwide coverage rather than relying on proximity-based systems like Apple’s Find My. That means live tracking and instant escape alerts no matter where your pet wanders—provided there’s LTE-M coverage. Fi also bundles the usual activity and sleep tracking that made their collars popular, and promises walking history and other location data in the companion app.

Battery life is the usual compromise for tiny devices: Fi advertises up to three weeks of on-device battery life, or up to three months if you use Fi’s optional base station that reduces power draw by acting as a local hub. The Mini supports a yearly membership, which Fi prices at about $129 per year (Fi’s launch materials also present the cost as a monthly equivalent with hardware included). In short, cheaper than the company’s flagship collar but still a subscription product.

Fi isn’t just shrinking hardware — it’s bringing software features over from its Series 3+ collar. Later this year, the Mini will receive an AI-powered behavior detection update that can flag patterns like barking, scratching, excessive licking, drinking and eating changes. Fi is also planning an Apple Watch integration so you can get key alerts on your wrist, bringing parity between the Mini and the Series 3+ ecosystem.

A compact GPS tracker aimed at cats and small dogs is a crowded playfield, but Fi’s angle is pedigree: the company built trust with its smart collar and is trying to port that experience to a clip-on that doesn’t force owners to switch collars. Compared to simple item trackers like AirTag (which rely on other nearby Apple devices to triangulate location), Fi’s LTE-M approach gives you direct live location even when your pet is far from other people or Wi-Fi.

That timing is notable. The broader pet-tracking market is shifting: Tractive recently acquired Whistle (a long-standing U.S. contender) and announced that the Whistle platform will wind down, pushing many users to transition to Tractive hardware and services. That consolidation may make an appealing opening for Fi to attract owners who want a new device—and for cat owners in particular, a small tracker that’s actually designed for felines.

You can order the Fi Mini now from Fi’s store and it’s slated to begin shipping on September 1, 2025. The device is sold with a membership; Fi lists the annual membership price at $129 (Fi’s launch materials also couch the cost as a monthly plan when hardware is included). If you want the longest possible battery life, plan on pairing the Mini with Fi’s optional base.

If you own a small dog or a cat that doesn’t tolerate bulk, the Fi Mini answers a real pain point: reliable, live GPS tracking in a package light enough not to make your pet look like it’s wearing a pendant. It isn’t a no-brainer—subscription cost and battery trade-offs matter—but the finished product feels like a meaningful option for pet owners who treat location and health insights as non-negotiable. With Whistle’s platform exiting and Tractive expanding, this could be Fi’s moment to win over owners who want a purpose-built, carrier-backed tracker that fits on a kitten’s collar.