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
Anvil Workout
Anvil Workout is a strength training app for iPhone
$2.99 · In-app purchases
PRICE
$2.99
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 Anvil Workout: 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
Add social features like challenges and friend connections to enhance motivation.
Assumption to check: Lack of user engagement features (e.g., challenges, community)
Validate with people who use this workflow before building.
Hypothesis 2
Incorporate workout templates and custom routines for diverse training options.
Assumption to check: Limited workout variety
Validate with people who use this workflow before building.
Hypothesis 3
Implement features for sharing progress on social media or within the app.
Assumption to check: No progress sharing options
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to customize their dashboard and workout plans based on preferences.
Assumption to check: Minimal personalization
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
Anvil Workout is a strength training app for iPhone. Plan your programs, track sets and reps in the gym, and review progress over time. One-time purchase — no subscription, no account, no ads, no in-app analytics. Your workouts stay on your device. PROGRAM LIBRARY Six classic strength programs are built in. Pick one, tap import, and start training: • Starting Strength • StrongLifts 5×5 • Greyskull LP • GZCLP • Upper/Lower split • Push/Pull/Legs Each program ships with the right exercises, set/rep schemes, and progression notes. Templates are fully editable after import. OR BUILD YOUR OWN Over 80 exercises across every major muscle group. Mix and match into your own routines, set targets for sets, reps, weight, and rest, and link supersets together. The exercise library is fully searchable. ACTIVE WORKOUT A focused screen for the gym floor. The current set is highlighted so you always know what's next. Bigger touch targets that work with sweaty fingers. Rest timer is readable from across the room. Lock Screen Live Activity keeps your workout visible without unlocking. PROGRESS TRACKING • Volume over time, weekly frequency, and 1RM estimates • Per-exercise history with personal records • Muscle group distribution • Weekly streak and quick-access to recent sessions on Home APPLE HEALTH Optional integration writes workouts to Health and reads heart rate and calories from Apple Watch during training. PRIVATE BY DEFAULT No account. No cloud. No analytics inside the app. Workout data stays on your device. Your progress is yours. PAID ONCE, YOURS FOREVER One-time purchase. No subscription. No upsells. Future updates included.
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
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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.
