Privacy-First AI Health Tracking

That "free" health app you're using? It's a data business. Here's the open-source tracker that keeps your records on your device — and still recognizes your food from a photo.

✓ Verified Free (T3) 🛠️ Open Source 📱 iOS + Android ⚠️ BYOK Required 📅 Verified: 2026-08-20

🧭 Which Health Tool Fits Your Privacy Needs?

Not all trackers are created equal. The right choice depends on your device, your goal, and how much privacy you want.

Your Device

What You Want to Track

Recommended: Fud AI

For iOS and food tracking, Fud AI is the most polished open-source option. Free Gemini key required for photo logging.

as of 2026-08-20

$20/month (MyFitnessPal) → $0 + Your Data Stays Private

as of 2026-08-20

"The smartest health app isn't the one that stores your data — it's the one that never sees it."
— Contrarian Take, Everyday AI Done Right

📱 Quick Pick by Platform

🍎 iOS → Fud AI

MIT licensed, 10-image meal scan, 873 exercises, Apple Watch, Gemini/OpenAI/Ollama [citation:5]

🤖 Android → FitBuddy

GPL-3.0, photo/text logging, offline simulator, OpenRouter/Gemini/Ollama, F-Droid [citation:2]

Step-by-Step Walkthrough

1 Stop trusting cloud-hosted health apps.

Contrarian Correction: Most guides tell you to download a popular tracker and let it analyze your health. That's backwards. These apps are data businesses first. The real win is using a bring-your-own-key (BYOK) app.

So What? If you use a closed-source tracker, your meal logs, weight, and health patterns are a product. With Fud AI or FitBuddy, they're yours. No account, no cloud sync by default.

2 Install the right app for your device.

iOS: Install Fud AI from the App Store. Open source, MIT licensed, no ads, no account [citation:5].
Android: Install FitBuddy from F-Droid. Open source, GPL-3.0, no ads, no tracking by default [citation:2].

3 Get a free Gemini API key.

Both apps use the same free tier:

Go to aistudio.google.com
Sign in with your Google account.
Click "Get API Key" — it's free.
Copy the key.

So What? Without this key, you can still log meals manually, but photo recognition requires it [citation:5]. The free Gemini tier gives you enough quota for daily tracking.

aistudio.google.com → Get API Key

Optional: Configure Ollama if you run a local LLM [citation:2].

4 Configure the app and log your first meal.

Open Settings → paste your Gemini API key.
Snap a photo of your food (Fud AI supports up to 10 images at once [citation:5]).
The AI estimates calories and macros instantly.
Review ingredients, adjust weights, and save.
Bookmark favorite meals as presets for one-tap logging next time [citation:2].

5 Track more than food.

Fud AI: 873 exercises with photos, barcode scanning, Apple Watch complications, water tracking, Siri shortcuts [citation:5].
FitBuddy: workouts, barcode scan, AES-256-GCM encrypted backups [citation:8].

Check your dashboard: daily calorie ring, combined food/exercise log, macro breakdown, custom charts tracking trends over time [citation:2].

⚠️ What Breaks (Limitations)

It's not a doctor. Both apps are trackers, not diagnosticians. So what? Trusting them to diagnose you could be harmful.
Bring-your-own-key required for photo logging. Free Gemini key takes 1 minute to create. So what? This is the privacy tradeoff — your data isn't stored on their servers, but you need to bring the AI.
Fud AI is iOS-only. Android users should use FitBuddy [citation:2].
FitBuddy is Android-only. iOS users should use Fud AI [citation:5].
No cross-device sync unless you use optional cloud backup (off by default in FitBuddy) [citation:8].

This guide is for informational purposes only. AI health tools are not substitutes for professional medical advice, diagnosis, or treatment.