cronos

Inspiration

We noticed something broken about every task manager on the market: they all assume you have time to manage your tasks. The irony is cruel — you're busy, so you need a task manager, but you're too busy to actually use one properly.

The moment that sparked Cronos was simple: we were driving, remembered three things we needed to do, and by the time we parked and opened a to-do app, we'd forgotten one of them. That's when it clicked — the input layer of productivity is fundamentally broken. It's still keyboard-first in a world where we talk to AI every day.

We asked: what if your task manager could listen, think, and act — not just store text? What if telling it "prepare for my AWS exam next month, also call the dentist Thursday afternoon, and pick up groceries every Monday" actually resulted in three perfectly structured, scheduled, repeating tasks — no typing, no tapping through menus? And what if the app could then research your exam prep for you, break it into study sessions, and pull resources from the web?

That's Cronos — a task manager that doesn't just hold your to-do list, it actively helps you get through it.

What it does

Cronos reimagines task management as an AI-first experience across iOS and Android.

🎙️ Voice-First Task Creation Speak naturally. Say "submit the quarterly report by Friday high priority, and schedule team standup every weekday at 9am" — Cronos transcribes it with OpenAI Whisper, then GPT-4o-mini parses the natural language into multiple fully structured tasks, each with its own title, due date, priority level, repeat schedule, and description. You review everything in a swipeable card UI before confirming.

🧠 AI That Understands Your Tasks Every task comes with an AI assistant powered by Perplexity Sonar. Tap the AI button on any task to:

Get a deep research brief with real-time web data, step-by-step checklists, pro tips, and cited resources Auto-generate sub-tasks — AI breaks a big goal into bite-sized, actionable pieces Chat conversationally about the task with full context awareness across multiple turns 🔄 Instant Cross-Device Sync Create a task on your iPhone, it appears on your Android within a second — powered by Supabase Realtime. Notifications reschedule themselves across devices. Complete a task from your lock screen on one device, and it updates everywhere.

⏰ Intelligent Notifications Snooze reminders for 5, 10, or 30 minutes directly from the notification. Set pre-notifications ("remind me 1 hour before"). Mark tasks done without ever opening the app. Repeating tasks auto-regenerate on completion.

💎 Production-Ready Monetization A custom-built paywall with a swipe-to-pay gesture, RevenueCat subscription management, and a genuine freemium model — this isn't a hackathon demo, it's a launchable product.

How we built it

I architected Cronos as a modular AI pipeline on top of a cross-platform mobile foundation:

Voice → Intelligence Pipeline: Raw audio (platform-adaptive: CAF on iOS, M4A on Android) → OpenAI Whisper transcription → GPT-4o-mini structured parsing with custom prompt engineering that handles multi-task commands, relative dates ("next Thursday"), and natural repeat expressions ("every other week"). The pipeline includes retry logic, format detection, and graceful degradation.

AI Intelligence Engine: A centralized orchestration layer that routes requests through Perplexity Sonar API with intelligent caching (MMKV-backed with TTL), rate limiting, and error recovery. One clean interface powers four distinct AI capabilities: task analysis, deep research, conversational chat, and sub-task generation.

Offline-First Architecture: Zustand state management persisted to MMKV (not AsyncStorage — 30x faster). Tasks work fully offline. A custom sync engine handles bidirectional Supabase sync with conflict resolution via timestamp comparison, self-trigger prevention using push-timestamp cooldowns, and debounced Realtime subscriptions.

Stack: React Native + Expo 54 (New Architecture), TypeScript, Supabase (Auth + Postgres + Realtime), NativeWind, Reanimated, Expo Notifications, RevenueCat.

Challenges we ran into

The "Two Seconds" Problem: Our entire voice pipeline — record → upload → transcribe → parse → display — had to feel instant. Users expect results within two seconds of pressing the mic button. We optimized audio encoding, minimized payload sizes, parallelized where possible, and tuned the GPT prompt to be lean enough to respond fast while still handling edge cases like "every other Tuesday except holidays."

Sync Storms: Real-time sync sounds simple until Device A pushes → Device B receives → Device B's state update triggers a push → Device A receives → infinite loop. We engineered a multi-layer defense: push-timestamp tracking, 1-second self-trigger cooldowns, 300ms realtime debouncing, and 30-second sync timeout circuit breakers. Getting this right took multiple iterations across real devices.

Audio Across Platforms: iOS records in CAF/Apple Lossless. Android records in M4A/AAC. Whisper expects specific formats. Emulators don't have real microphones. We built an entire platform-adaptive recording layer with format detection, sample rate normalization, and fallback mechanisms — invisible to the user, but crucial for reliability.

Making AI Useful, Not Gimmicky: The temptation with AI features is to slap a chatbot on something and call it innovative. We pushed ourselves to make every AI interaction actionable. Research generates checklists you can save. Sub-tasks get added to your actual task list. Chat responses include citations you can open. The AI doesn't just talk — it produces artifacts you use.

Accomplishments that we're proud of

Multi-task voice parsing — speak one sentence with three different tasks, and three distinct, correctly structured task cards appear with individual dates, priorities, and repeat schedules. No other mobile task manager does this. AI research that's actually useful — not generic ChatGPT responses, but Perplexity-powered research with real-time web data, structured into Overview, Checklist, Tips, and Resources tabs — with working citations. Sub-second cross-device sync — we built a production-grade sync engine with conflict resolution, not a demo. Tasks, completions, snooze states, and notifications all propagate across devices in under a second. Offline-first with seamless rehydration — use the app on a plane, and everything syncs perfectly when you land. Zero data loss, zero conflicts. Shipping a real product — this isn't a prototype. Cronos has authentication, a subscription model, a custom paywall with swipe-to-pay, dark mode, haptic feedback, and runs natively on both iOS and Android. It's ready for the App Store

What we learned

AI integration is a design problem, not just an engineering one. The hardest part wasn't calling APIs — it was deciding where AI should intervene and where it should stay out of the way. We learned that the best AI features are the ones users don't think of as "AI" — they just think the app is really smart.

Prompt engineering is underrated software engineering. Our GPT parsing prompt went through 15+ iterations. Handling "every other Tuesday," "next week sometime," "high priority," and "also remind me to..." in a single utterance requires careful instruction design, structured output formats, and extensive testing.

Cross-platform means cross-everything. Audio codecs, notification behaviors, gesture handling, haptic APIs, file system paths — the differences between iOS and Android run deeper than the UI. True cross-platform quality requires treating each platform's quirks as first-class engineering problems.

Offline-first isn't optional for mobile. We initially treated sync as the primary path and offline as a fallback. Flipping that mental model — offline-first, sync as enhancement — led to a fundamentally more reliable architecture.

What's next for cronos

Adding more features and polished onboarding:

🔌 MCP Integration (Model Context Protocol) — This is the big one. I am building Cronos as an MCP-enabled platform, turning it into a universal AI task hub. Imagine connecting Cronos to your Gmail, Slack, Jira, Google Calendar, or GitHub through MCP servers — and your AI assistant suddenly has full context across your entire workflow. Say "create tasks from my unread emails" or "what's blocking the sprint?" and Cronos pulls live data through MCP to give you real, actionable answers. MCP makes Cronos more than a task app — it becomes the AI orchestration layer for your entire productivity stack. 🤝 Shared Task Lists — collaborative task management with family and teammates. 📍 Location-Aware Task Surfacing — Walk into a grocery store, and Cronos surfaces your shopping tasks. Arrive at the office, and work tasks pop up. Leave the gym, and it reminds you to log your workout. Tasks appear when and where they're relevant, not buried in a list. 🗣️ Multiplayer Voice Rooms — In a team meeting, everyone has Cronos open. One person says "Okay, Rishabh will handle the backend, Priya takes design, and we need the API docs by Thursday." Cronos creates and assigns tasks to each person in real-time from a shared voice stream. Meetings become productive without anyone taking notes. 📊 Habit Analytics — leverage the repeat system to track streaks, completion rates, and surface productivity patterns 🌐 Public Launch — App Store and Play Store submission with polished onboarding and a growth engine

Built With

• android-(single-codebase)-other:-expo-secure-store
• axios
• chat
• complete-from-lock-screen)-monetization:-revenuecat-(subscription-management
• date-fns
• expo-blur
• expo-file-system
• expo-haptics
• expo-router-ai-/-apis:-openai-whisper-(speech-to-text)
• expo-sdk-54
• gpt-4o-mini-(natural-language-parsing)
• in-app-purchases)-ui-&-styling:-nativewind-(tailwindcss-for-react-native)
• javascript-framework:-react-native-(0.81
• languages:-typescript
• lucide-icons-audio:-expo-av-(cross-platform-voice-recording-with-platform-adaptive-encoding)-platforms:-ios
• new-architecture)
• perplexity-sonar-api-(research
• react-native-reanimated-(animations)
• sub-task-generation)-backend-&-database:-supabase-(postgresql-+-auth-+-realtime-subscriptions)-state-management:-zustand-with-mmkv-persistence-(offline-first)-notifications:-expo-notifications-(actionable-categories-?-snooze
• uuid