Compare: Whistle vs Fi Pet Tracker Apps

Contact us to report infringement

By Dallas Hughes | App Reviews Column | The Pet Standard

If you've ever sprinted through a park shouting your dog's name while holding a soggy lead and wearing one slipper, you’ve probably thought, There must be an app for this. 

Good news: there is. In fact, there are two leading pet tracker apps competing for that prime spot on your home screen Whistle and Fi.

Both claim to track your pet’s every move, monitor their health, and basically parent them better than you do. But which one’s worth the money, the app storage, and your dog’s eternal side-eye at being micro-managed?

I’ve tested both with my overly curious spaniel, Rufus, and my "you don’t own me" cat, Margot (spoiler: she declined to participate). Let’s compare these techy tail trackers head to tail.

The Basics: What Are Whistle and Fi?

Both Whistle and Fi are GPS-enabled pet tracking systems that connect via collar-mounted devices and smartphone apps.

They aim to solve pet parents' most pressing issue: Where is my dog and what is he doing now and is it legal?

Here’s a quick overview:

Feature	Whistle	Fi
GPS Tracking	Yes	Yes
Health Monitoring	Yes	No
Activity & Sleep Data	Yes	Yes
Escape Alerts	Yes	Yes
Subscription Required	Yes	Yes
Battery Life	~10 days	Up to 3 months
UK Availability	Limited	No (yet)

Round 1: GPS Tracking Accuracy

Whistle:

Whistle uses AT&T’s network in the US for GPS tracking, paired with Wi-Fi and Bluetooth. In terms of accuracy, it’s generally solid provided you’re in a good coverage area. In UK trials (with some trickery and a VPN), it performed decently, but was clearly not optimised for Britain. The updates lagged slightly, and rural areas were hit-and-miss.

Fi:

Fi uses LTE-M networks and claims real-time tracking with escape alerts. And yes, it’s pretty impressive if you live in the United States. Sadly, as of 2025, Fi is still not officially available in the UK, which makes it more of a theoretical comparison for British pet owners… unless you’re feeling particularly rebellious and tech-savvy.

Verdict: Fi wins for GPS, but only if you’re on the right continent. Whistle struggles in the UK, but is at least possible to use.

Round 2: Health and Activity Monitoring

Whistle:

This is where Whistle shines. The app tracks your dog’s daily activity, calories burned, sleep quality, and even scratching or licking patterns useful if you suspect allergies or anxiety. You can share all this data with your vet, who may or may not be thrilled to receive a 12-page PDF on your cockapoo’s REM cycles.

Fi:

Fi is more focused on steps and sleep, like a simplified Fitbit for your dog. It’ll let you know if Rufus hit his step goal or slept poorly (though he's clearly exhausted from barking at squirrels). There's no detailed health monitoring yet.

Verdict: Whistle takes the biscuit here. It’s part vet assistant, part helicopter parent.

Round 3: App Design and Usability

Whistle:

The Whistle app is intuitive, colourful, and full of data but perhaps too full. It's a data-lover’s dream and a casual user’s mild anxiety attack. Prepare for charts, graphs, and the occasional “Your dog is 7% less active than yesterday” guilt trip.

Fi:

Fi’s app is sleek, minimalistic, and focused on what you care about: Where is my dog, and is he alive? It delivers alerts instantly, and its lost dog mode is one of the fastest responders in the market.

Verdict: Fi is cleaner, but Whistle offers more. Depends if you want simplicity or nerdy detail.

Round 4: Battery Life

• Whistle: About 10 days on average, depending on how often GPS is pinged.

• Fi: Up to 3 months on a single charge, which is frankly ridiculous and makes you question why your phone can’t do that.

Verdict: Fi, by a mile. It’s the Tesla of dog collars.

Round 5: Pricing

Both apps require subscriptions to unlock full tracking features.

Plan	Whistle	Fi
Device Price	~$129 (£100)	~$149 (£115)
Subscription	~£7/month	~£6/month
UK Availability	Sort of	Not yet

Note: As of writing, Fi is not officially available in the UK, and Whistle’s GPS coverage is patchy outside of major US cities. So for British users, both come with caveats.

Verdict: Fi is cheaper long-term, but if you’re UK-based, you’ll get more functionality out of Whistle if you can get it working.

Science Check: Are These Devices Evidence-Based?

Yes both Whistle and Fi use positive reinforcement training principles, GPS tech, and health metrics grounded in behavioural research. Whistle's health alerts, in particular, have been praised by vets for their ability to detect early signs of trouble (like excessive licking, a potential marker for skin irritation or anxiety).

The science is solid the real question is whether the tech translates well for your particular dog and your postcode.

Final Verdict: Should You Buy One?

If you’re in the UK, the sad truth is: neither Whistle nor Fi works perfectly here yet.

• Whistle is semi-functional with a workaround, but not ideal.

• Fi is better on paper (and in practice in America) but still not available on British shelves.

That said, if you're a tech enthusiast with a clever workaround and don’t mind a bit of faff, Whistle can give you loads of insight into your dog’s health and movements. If you’re in the US? Fi’s probably the smartest pet tracker on the market.

British alternative to consider: Tractive GPS Tracker – fully UK-compatible, decent battery life, and widely used by vets and trainers alike.