Fi vs Function Health
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Fi
This app pairs with a smart collar to provide real-time GPS tracking for your dog. Monitor their activity, health patterns, and receive alerts if they leave designated safe zones. It offers peace of mind for pet owners by keeping them connected to their canine companions.
- Real-time GPS tracking
- Geofencing and escape alerts
- Activity and health monitoring
- AI behavior insights
- Lost Dog Mode
- Long battery life
- Apple Watch integration
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Fi Series 3+ is the world's smartest GPS dog collar—now powered by AI. Paired with a Fi collar, the Fi app brings you even closer to your dog. Track their location, monitor activity and health patterns, and get alerts if they ever leave a safe zone. It's peace of mind for the best pet parents out there. FEATURES GPS TRACKING On vacation? Friend walking the dog? Instantly track your dog's location no matter where they are. Fi gives you the confidence to know they're safe from anywhere, anytime. STOP ESCAPE ARTISTS Designate safe zones around your home or dog's favorite places. If they leave without a trusted person, we'll alert you immediately. So if they wander anywhere, you'll be the first to know. ACTIVITY MONITORING Track your dog's step count daily and start streaks by achieving custom goals you set. Then see how they compare with similar dogs in the Fi community. Every step goes a long way toward keeping them happy and healthy. AI BEHAVIOR INSIGHTS Fi Series 3+ tracks more than just steps. Spot trends in activity, rest, scratching, licking, drinking, eating, and barking so you can stay in tune with your dog's health and habits, every day. LOST DOG MODE Never lose track again. If your dog goes missing, activate Lost Dog Mode to turn on rapidly refreshing live location updates until they're found. BATTERY LIFE With best-in-class battery, our collars lasts up to 3 months on a single charge. No other collar even comes close. SUPPORT Need help? We're here for you and your dog. Our support team is just a chat or phone call away when you need. APPLE WATCH INTEGRATION With our all new Series 3+, you can view your dog's location and activity directly on your wrist, so you're always connected, even without your phone. OUR COLLAR Available in 4 different colors and 5 different sizes to fit dogs of all sizes. Fi works best when connected near a Bluetooth connected device with the Fi App or the provided charging base. The latest iOS version is required to run Fi. Learn more about what we're building at: www.tryfi.com.
Function Health
Take control of your health with comprehensive lab testing, personalized protocols, and AI-powered insights. Understand your body's data, track changes over time, and make informed decisions for long-term wellness. Connect wearables and upload records for a complete health picture.
- 160+ lab tests annually
- Personalized health protocols
- Private AI Chat for results
- Connect health wearables
- Advanced MRI & CT scans
- Upload health records
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Function membership helps you take control of your health with 160+ lab tests each year, personalized Protocols, and Private AI Chat—all backed by advanced science and your real data. Built with top doctors, Function gives you the power to understand your body, track how it evolves, and make meaningful change. NOW AVAILABLE: HOME OR OFFICE BLOOD DRAWS Schedule a concierge blood draw at your home or office. A licensed specialist comes to you and completes your blood draw in under 20 minutes. Available in select locations. 160+ LAB TESTS Membership includes testing for your heart, hormones, thyroid, liver, kidneys, toxins, nutrients, inflammation, autoimmunity, immunity and more. ADVANCED MRI & CT SCANS Detect early signs of cancer and hundreds of other potential conditions with the option to purchase advanced imaging for your brain, pancreas, liver, spine, ovaries, prostate, heart and much more. PRIVATE AI CHAT Ask questions about your results, identify meaningful patterns, and figure out where to focus next, with Private AI Chat—built in partnership with top clinicians. CONNECT WEARABLES Connect Apple Health and other health devices and wearables to see how your activity, sleep, and daily habits affect your lab test results and long-term health. PROTOCOLS Translate your lab results, scans and health history into clear, evidence-based plans for nutrition, activity, and supplements—all customizable to your goals and preferences. UPLOAD HEALTH RECORDS Upload past lab test results, scans, and other medical records for a more complete view of your health, all in one secure place. PROGRESS YOU CAN SEE Twice-yearly and On-Demand testing helps you track your results over time, monitor for early signs of disease, and identify where to focus next. ADVANCED LAB TESTS Membership includes 160+ lab tests, plus the option to purchase advanced On-Demand tests for: - Detection of 50+ cancers - Alzheimer’s risk detection - MTHFR gene variants - Advanced MRI and CT scans starting at $365 - Food allergies and sensitivities - …and much more ACCESSIBILITY What could cost as much as $15,000 on your own is included with membership for just $365/year. Lab testing is available at over 2,000 lab locations across the US, with no insurance needed. SECURITY Function was built for privacy and security. Function is built to HIPAA standards. Your information is secure. How it works: 1. Join Function and schedule your first set of lab tests. 2. Get your results and personalized Protocols. Ask questions with your Private AI Chat. 3. See your progress with 60+ lab tests at your Mid-Year Test. 4. Purchase MRI or CT scans and other advanced On-Demand Tests any time. DISCLAIMER Function Health is a technology company and not a laboratory or medical provider. All laboratory and medical services are provided by independent third parties. Function Health does not offer medical advice, laboratory services, a diagnosis, medical treatment, or any form of a medical opinion; its services are not a substitute for medical care, medical advice, and/or a detailed discussion with a physician or other licensed provider. If you have any questions regarding any laboratory results or any other information that you access through Function Health, you should contact a physician or other licensed provider. All material, information, data, and content that Function Health provides is strictly for general information purposes. For additional important information: https:// www.functionhealth.com/terms-of-service.
Screenshots
Verdict
The clearest difference is monetization model: Fi at free against Function Health's subscription. Fi also leads on device support (3 vs 1). Function Health's advantage is review sentiment (62% vs 38%) and rating (4.9 vs 4.6). On price, ratings volume, update cadence and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Function Health holds the better App Store score, 4.9 against 4.6. Both are backed by a comparable volume of ratings — 42K and 25K respectively. Written reviews point the same way: 38% of Fi's written reviews are positive against 62% of Function Health's.
Both ship on a similar rhythm, roughly weekly. Both last shipped on October 20, 2026.
| Parameter | Fi | Function Health |
|---|---|---|
| Price | Free | Free |
| Rating | 4.6 (42K ratings) | 4.9 (25K ratings) — better |
| Positive reviews | 37.9% of reviews | 61.8% of reviews — better |
| Number of ratings | 42K — better | 25K |
| Update frequency | Weekly | Weekly |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Subscription |
| Best chart rank | — | #193 — better |
| Devices | iPhone, iPad, Apple Watch — better | iPhone |
| Requires iOS | 17.0 | 16.4 — better |
| Further details — not scored | ||
| Size | 197 MB | 203 MB |
| Age rating | 4+ | 17+ |
| Developer | Barking Labs Corp. | Function Health |
Customer experience
Fi
Function Health
User reviews
Fi
From 42K App Store ratingsWhat we love
- 🚀 Accurate GPS tracking
- 🔒 Provides peace of mind
- 👍 Helpful customer service
- 🚀 Long battery life
- 👍 Waterproof collar
Room to improve
- 🐛 Inaccurate GPS location
- 🔋 Battery drain issues
- 🐛 Unreliable connectivity
- 👎 Intrusive notifications
- 👎 Difficult to cancel subscription
Function Health
From 25K App Store ratingsWhat we love
- 🚀 Seamless process for blood tests and results
- 📊 Comprehensive health insights and tracking
- 🧠 Helpful clinician notes and recommendations
- 👍 User-friendly and visually appealing app
- 💰 Affordable compared to other options
Room to improve
- 🔍 Lack of communication and support responsiveness
- 🐛 Some bugs and usability issues in the app
Bugs and requests
Fi
Reported bugs
3 issues- Collar stops working unexpectedly
- App glitches and crashes
- GPS tracking lags or shows incorrect locations
Requested features
5 requests- Customizable notification settings
- Offline step/distance tracking
- Ability to edit/delete activity data
- More accurate geofencing options
- Integration with other apps (e.g. Wag)
Function Health
Reported bugs
2 issues- App sometimes redirects back to the home screen when trying to view results
- Occasional typos and formatting issues in the app
Requested features
3 requests- More customization options in the app settings
- Ability to print or export test results and recommendations
- Specific supplement recommendations rather than broad suggestions
In-app purchases
Fi
No in-app purchases
Function Health
No in-app purchases








