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
LiftKit: Gym Workout Log
You go to the gym to lift, not to manage subscriptions or fight with cluttered apps
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
1 ratings · Top 5%
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.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included17 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 LiftKit: Gym Workout Log: 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
Expand exercise library and allow user-uploaded exercises.
Assumption to check: Limited workout variety and exercise database.
Validate with people who use this workflow before building.
Hypothesis 2
Include HealthKit and Google Fit integration for enhanced tracking.
Assumption to check: No integration with health tracking APIs.
Validate with people who use this workflow before building.
Hypothesis 3
Add advanced analytics and personalized insights based on user data.
Assumption to check: Basic progress tracking features.
Validate with people who use this workflow before building.
Hypothesis 4
Offer more free content or a one-time purchase option.
Assumption to check: Subscription model could deter 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
You go to the gym to lift, not to manage subscriptions or fight with cluttered apps. I built LiftKit to be a gritty, no-nonsense tracker built to get out of your way so you can focus on what matters: moving weight. Why LiftKit is your new training partner: Own Your Tools: Stop renting your workout history. With one fair price, you secure a lifetime of tracking without ever seeing a monthly bill. Track What Matters: Instantly see your PRs to adjust goals, volume, and progressive overload trends without digging through confusing menus. I only made this a 3 Tab system! Privacy First: This mattered to me the most! Your data lives on your device, not on a server. No tracking, no data selling, no creeping. My Guarantee: LiftKit is built by a solo developer college student, not a tech giant trying to squeeze you for profit. I built this to serve you. I also use this app everyday so If you ever need help or want a new feature, you can talk directly to me through the request form. (Give me some time to respond) Simple. Strong. Yours. Download LiftKit today and replace your notebook forever.
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
Zustand
react-navigation
react-native-chart-kit
expo-secure-store
BUILD KIT DIFFICULTY
Starter
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.
