Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
TimeFast
TimeFast is the intermittent fasting timer that respects your privacy
$6.99 · In-app purchases
PRICE
$6.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
Build your own version
Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included16 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for TimeFast: map the core Health & Fitness workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Focus on user experience improvements and gather user feedback to enhance the app.
Assumption to check: Lack of user reviews can indicate poor user engagement or issues.
Validate with people who use this workflow before building.
Hypothesis 2
Introduce a competitive free trial or freemium model to attract more users.
Assumption to check: High price point may deter users from trying the app.
Validate with people who use this workflow before building.
Hypothesis 3
Add unique features like personalized workout plans, social sharing, or gamification elements.
Assumption to check: Limited features compared to other fitness apps.
Validate with people who use this workflow before building.
Hypothesis 4
Simplify navigation with clear labels and a guided onboarding process.
Assumption to check: Complex navigation may confuse users.
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
TimeFast is the intermittent fasting timer that respects your privacy. Start your fast with one tap, watch a beautiful progress ring track every minute, and see exactly which fasting phase you're in. No account needed, no subscription, no data ever leaves your device. Whether you follow 16:8, OMAD, or your own schedule — TimeFast adapts to you, not the other way around. FASTING PROTOCOLS FOR EVERY GOAL - 6 proven protocols: 12:12, 14:10, 16:8, 18:6, 20:4, and OMAD (23:1) - Create custom fasting plans with any duration from 1 to 72 hours - Difficulty indicators from beginner to expert to help you progress REAL-TIME FASTING TRACKER - Animated progress ring showing elapsed and remaining time - Live countdown timer with hours, minutes, and optional seconds - Fasting phase timeline shows your body's stages: fat burning (12h), ketosis (16h), autophagy (24h) - Percentage-based progress at a glance - Forgot to start? Adjust your start time retroactively FASTING JOURNAL & SESSION DETAILS - Detailed breakdown for every completed fast - See which metabolic phases you reached - Add personal notes and reflections to any session - Track your achieved percentage and duration STREAKS, HISTORY & STATISTICS - Daily streak counter to build your fasting habit - Full session history with interactive calendar view - Success rate, average fasting duration, and total hours tracked - Visual streak badge to keep your motivation high HOME SCREEN & LOCK SCREEN WIDGETS - Small and medium Home Screen widgets for at-a-glance status - Circular and rectangular Lock Screen widgets for quick checks - Live progress updates while fasting - Streak display when you're in your eating window SMART REMINDERS - Get notified when your fast is complete — even while the app is open - Set a daily reminder to start your fast at the time that works for you DESIGNED WITH LIQUID GLASS - Built natively for iOS 26 with Apple's Liquid Glass design - Refined dark-mode interface with translucent glass surfaces - No account required — works immediately out of the box - One-time purchase — no subscription, yours forever PRIVACY BY DESIGN TimeFast stores all data exclusively on your device. No data is collected, transmitted, or shared with anyone. Zero analytics, zero third-party SDKs, zero server connections. Your fasting data belongs to you alone. Available in English and German. All interface elements adapt to your system language.
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Supabase
TypeScript
Zustand
react-native-reanimated
BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
