fud-ai

Introduction: Fud AI is a Free & Open Sourced AI Calorie Tracker for iOS & Android

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Fud AI Logo

Fud AI

Eat Smart, Live Better
Snap, speak, or type your food — AI handles the rest.

Open-source, privacy-first calorie tracker for iOS and Android. Bring your own AI provider — 13 supported including Gemini, OpenAI, Claude, Grok, Groq, Hugging Face, Fireworks AI, DeepInfra, Mistral, and any custom OpenAI-compatible endpoint. Open-weight models (Gemma, Llama Vision, Qwen VL, Pixtral) work out of the box. Snap a meal, ask your AI coach how to hit your goal, speak your lunch. All data stays on your device. No accounts, no cloud sync, no tracking, no subscriptions.

App Store · Google Play · Website · Report an Issue · Request a Feature

Logging

Snap food — camera identifies meals and estimates nutrition
Camera + Note — add a description with the photo for better accuracy
Nutrition label scan — reads packaging for precise per-serving data
Photo library — analyze existing photos
Text input — type food descriptions
Voice input — speak your meals hands-free (5 STT providers, see below)
Saved Meals — Recents, Frequent, and Favorites with swipe-to-delete and drag-to-reorder

Intelligence

AI Coach tab — multi-turn chat with memory. Coach sees your profile, weight history, and food log and answers questions like "what's my expected weight in 30 days?" or "how do I lose 2 kg?". Memory persists across launches; Reset button starts a fresh conversation. Long-press any reply to copy.
Goal-aware prompt chips — suggested questions change based on whether your goal is Lose / Gain / Maintain
Thermodynamic weight forecast — expected weight at 30/60/90 days, predicted vs observed weekly change, days-to-goal, under-logging detection. Surfaced through Coach as live context on every turn.
Resilient requests — transient provider overloads (503 / 529 / 429) auto-retry with 1s / 2s / 4s exponential backoff across both food analysis and Coach chat, so short spikes resolve invisibly

Tracking

13 nutrients per entry (calories, protein, carbs, fat + 9 micronutrients)
Scrollable week calendar — swipe to any past week, configurable start day
Progress charts — weight trends, calorie history, macro averages (1W to All Time)
Weight History — tap-to-delete past entries, syncs deletion to Apple Health
Goal tracking — set target weight, BMR/TDEE auto-calculation; goal-reached alert fires from both manual logs and Apple Health reads

Health & platform

Apple Health — bidirectional sync for body measurements + 12 nutrition types written per meal
Widgets — Home Screen (small / medium with calorie ring + macro bars) and Lock Screen (circular / rectangular / inline). Update live whenever you add or delete a meal — no tap-to-open-app needed
Share the App — native iOS share sheet from About → forwards App Store URL plus a personalized message and fud-ai.app link; message body localized into all 15 languages
15 languages — Arabic, Azerbaijani, Dutch, English, French, German, Hindi, Italian, Japanese, Korean, Portuguese (Brazil), Romanian, Russian, Simplified Chinese, Spanish (auto-selected by iPhone's Language setting)
Meal reminders — customizable breakfast, lunch, dinner notifications
Dark mode — system, light, or dark
Metric & imperial units

AI Providers

Pick any of the 13 LLM providers for both food analysis and the Coach chat. Free Gemini keys are available at aistudio.google.com/apikey.

Provider	Format	Highlight	Needs API Key
Google Gemini	Gemini API	Gemini 2.5 Pro / Flash	Yes
OpenAI	OpenAI	GPT-5 / 4o	Yes
Anthropic Claude	Messages API	Sonnet 4.6 (default) / Opus 4.7 / Haiku 4.5	Yes
xAI Grok	OpenAI-compatible	Grok 4	Yes
OpenRouter	OpenAI-compatible	Any model, free-form IDs	Yes
Together AI	OpenAI-compatible	Llama 4, Qwen VL	Yes
Groq	OpenAI-compatible	Llama 4 Scout, very fast	Yes
Hugging Face	OpenAI-compatible	Gemma 3, Qwen VL, Llama Vision (open-weight router, free-form IDs)	Yes
Fireworks AI	OpenAI-compatible	Qwen VL, Llama Vision, Phi-3 Vision	Yes
DeepInfra	OpenAI-compatible	Gemma 3, Llama Vision, Qwen VL	Yes
Mistral	OpenAI-compatible	Pixtral Large / 12B (open-weight)	Yes
Ollama	OpenAI-compatible (local)	Llama 3.2 Vision, LLaVA, Moondream — runs on your Mac	No
Custom (OpenAI-compatible)	OpenAI-compatible	You set base URL + free-form model name	Optional

Speech-to-Text Providers

Pick how voice input is transcribed. Native iOS is the default — free, on-device, real-time.

Provider	Notes
Native iOS (On-Device)	Free, offline on modern iPhones, real-time partial results
OpenAI Whisper	Whisper-1 via `/v1/audio/transcriptions`
Groq (Whisper)	Whisper-large-v3, very fast, has a free tier
Deepgram	Nova-3, fast and accurate
AssemblyAI	Universal model, strong accuracy, free tier

All API keys are stored in iOS Keychain — encrypted, on-device only.

How It Works

Photo / Text / Voice
        │
        ▼
  AI Provider API  ──▶  JSON nutrition response
        │
        ▼
  User reviews & edits
        │
        ▼
  FoodStore.addEntry()  ──▶  UserDefaults (local) + Apple Health (optional)

For the Coach chat, every turn builds a slim system prompt from your live profile, BMR formula in use, computed forecast, and a one-line snapshot of available data. Coach then pulls any date range of weight, body fat, calorie totals, or food entries on demand via tool calling — ask "what was my weight in March?" or "show me my body fat trend over the last 6 months" and it fetches exactly the slice it needs.

Screenshots

A seven-step walkthrough of the app's core flow — from opening the dashboard to reviewing long-term trends.

01 · Home · Dashboard _{Daily calorie ring, macro bars (P / C / F), and today's logged meals grouped by meal type. Week strip at the top for date navigation.}	02 · Log · Options _{Tap + to open the entry menu: Camera, Camera + Note, Nutrition Label scan, From Photos, Text Input, Voice, or Saved Meals.}	03 · Snap · Capture _{Point and shoot. The image is sent to your chosen AI provider; nutrition estimates come back within a few seconds.}
04 · Review · Edit _{Review the AI's guess, adjust the serving size (everything recalculates live), and pick a meal type before logging.}	05 · Meals · Log _{The day's entries grouped by breakfast / lunch / dinner / snack. Swipe to delete, tap to edit any entry.}	06 · Coach · AI Chat _{Multi-turn conversation with full context of your profile, weight history, food log, and forecast. Ask "what should I eat?" or "expected weight in 30 days?".}
07 · Progress · Charts _{Weight trend with goal line, calorie history (intake vs. goal), and macro averages. Time ranges span 1 week to all time.}

Calorie & Macro Calculation

The app calculates personalized daily targets using established nutrition science formulas:

Step	Formula	Details
BMR	Katch-McArdle	`370 + 21.6 × lean mass (kg)` — used when body fat % is known
BMR	Mifflin-St Jeor	`10w + 6.25h − 5a ± 5` — fallback when body fat is unknown
TDEE	BMR × activity	Multiplier ranges from 1.2 (sedentary) to 2.0 (extra active)
Daily Calories	TDEE + adjustment	Adjustment = `weeklyChangeKg × 7700 / 7` (deficit or surplus)
Protein	Activity + goal	`0.8 – 2.2 g/kg` by activity, plus +0.2 g/kg during cutting phase (Helms et al 2014)
Fat	Fixed ratio	`0.6 g/kg` body weight
Carbs	Auto-balanced	Remainder from calories − protein − fat (any macro can be pinned; max 2 pinned)

All values can be manually overridden in Settings, with a Recalculate Goals button to snap back to formula defaults.

Architecture

Component	Details
Language	Swift 5, SwiftUI, iOS 17.6+
Storage	UserDefaults (local JSON), Keychain (API keys)
AI	`GeminiService` for food + label analysis, `ChatService` for multi-turn Coach chat, both route across all 13 providers
Speech	Native `SFSpeechRecognizer` or remote providers via `SpeechService` (m4a upload)
Health	HealthKit read/write (body measurements + 12 nutrition types) with background observers, UUID-tagged samples for safe delete
Pattern	`@Observable` + `.environment()`, main actor isolation
Localization	`Localizable.xcstrings` (String Catalog), 15 languages, auto-selected by iPhone's system language
Dependencies	Zero

Repo Layout

fud-ai/
├── ios/          # SwiftUI iOS app (shipping on App Store, v3.2)
├── android/      # Kotlin + Jetpack Compose app (min SDK 26 / Android 8.0, v1.0.6)
├── web/          # Marketing site — https://fud-ai.app (static HTML/CSS, Vercel)
├── APPSTORE.md   # App Store Connect listing copy (iOS)
├── PLAYSTORE.md  # Google Play Console listing copy (Android)
└── README, LICENSE, CONTRIBUTING, SECURITY, CLAUDE.md, .github/

Source Layout (iOS)

ios/
├── calorietracker.xcodeproj/         # Xcode project
├── calorietrackerTests/              # Unit test target (boilerplate)
├── calorietrackerUITests/            # UI test target (boilerplate)
├── FudAIWidgets/                     # Widget extension target (Home + Lock Screen)
├── screenshots/                      # README screenshots
└── calorietracker/
    ├── calorietrackerApp.swift       # Entry point, environment setup
    ├── ContentView.swift             # 5-tab layout (Home, Progress, Coach, Settings, About)
    ├── Localizable.xcstrings         # String Catalog, 15 languages
    ├── Models/
    │   ├── AIProvider.swift          # 13 LLM providers, model lists, settings
    │   ├── SpeechProvider.swift      # 5 STT providers + Keychain settings
    │   ├── ChatMessage.swift         # Coach chat message model
    │   ├── UserProfile.swift         # BMR/TDEE/macro calculations
    │   ├── FoodEntry.swift           # Food item with 13 nutrients
    │   └── WeightEntry.swift         # Weight log entry
    ├── Views/
    │   ├── OnboardingView.swift      # 15-step onboarding flow
    │   ├── ChatView.swift            # Coach tab: bubbles, prompt chips, reset
    │   ├── FoodResultView.swift      # AI result review & edit
    │   ├── RecentsView.swift         # Saved Meals (Recents / Frequent / Favorites)
    │   ├── VoiceInputView.swift      # Native + remote STT routing
    │   ├── HomeComponents.swift      # Week strip, macro cards
    │   └── ProgressComponents.swift  # Charts, weight history
    ├── Services/
    │   ├── GeminiService.swift       # Food/label analysis, routes 13 providers
    │   ├── ChatService.swift         # Multi-turn Coach chat, routes 13 providers
    │   ├── SpeechService.swift       # Remote STT router (OpenAI / Groq / Deepgram / AssemblyAI)
    │   ├── WeightAnalysisService.swift # Thermodynamic weight-forecast math
    │   ├── KeychainHelper.swift      # iOS Keychain wrapper
    │   └── APIKeyManager.swift       # Keychain migration helper
    └── Stores/
        ├── FoodStore.swift            # Food CRUD + favorites
        ├── WeightStore.swift          # Weight CRUD (auto-syncs profile weight)
        ├── ProfileStore.swift         # @Observable wrapper over UserProfile
        ├── ChatStore.swift            # Coach chat history (persisted locally)
        ├── NotificationManager.swift  # Notification scheduler
        └── HealthKitManager.swift     # Apple Health bridge (body + nutrition)

Build & Run

# Clone
git clone https://github.com/apoorvdarshan/fud-ai.git
cd fud-ai

iOS

xcodebuild -project ios/calorietracker.xcodeproj \
  -scheme calorietracker \
  -destination 'platform=iOS Simulator,name=iPhone 17 Pro' build

Open ios/calorietracker.xcodeproj in Xcode, select your device, and run.

Android

Open android/ in Android Studio (Narwhal or newer), let Gradle sync, hit ▶ Run. Or from the CLI:

export JAVA_HOME="/Applications/Android Studio.app/Contents/jbr/Contents/Home"
cd android
./gradlew :app:assembleDebug
adb install -r app/build/outputs/apk/debug/app-debug.apk
adb shell am start -n com.apoorvdarshan.calorietracker/.MainActivity

First launch walks you through a 15-step onboarding (gender, birthday, height/weight with metric/imperial toggle, body fat %, activity, goal, goal speed, notifications, Health Connect, AI provider + API key, plan preview, review). A free Gemini key is available at aistudio.google.com/apikey. You can switch providers anytime in Settings → AI Provider.

Contributing

See CONTRIBUTING.md for guidelines. Bug reports and feature requests welcome.

Adding a new translation? Open ios/calorietracker/Localizable.xcstrings in Xcode and fill in your language column — everything else is already wired.

Security

See SECURITY.md. Use private vulnerability reporting for sensitive issues.

Privacy

All data stays on your device. No accounts, no cloud sync, no analytics. API keys are stored in iOS Keychain. Delete All Data is local-only — it wipes the app's storage (food log, weight log, profile, Coach chat, API keys, widget snapshot) but never touches Apple Health. Samples you've synced are yours; if you want them cleaned up, do it from Health → Sources → Fud AI. See Privacy Policy.