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
SpeedUp Player Pro +
Listen to your iPod collections at 0.5X - 2.5X speed
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
185 ratings · Top 15%
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/
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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 SpeedUp Player Pro +: map the core Productivity 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
Broaden supported formats, including FLAC and OGG.
Assumption to check: Limited audio format support.
Validate with people who use this workflow before building.
Hypothesis 2
Implement smoother playback transitions.
Assumption to check: Inconsistent playback speed adjustments.
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to download and play tracks offline.
Assumption to check: No offline access to saved tracks.
Validate with people who use this workflow before building.
Hypothesis 4
Add waveform and visualizers for enhanced engagement.
Assumption to check: Lack of audio visualization features.
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
Listen to your iPod collections at 0.5X - 2.5X speed. Supports multitasking, remote controller. Study mode(A/B repeat, quick rewind/forward), sleep timer. * Save time listening to podcasts and audiobooks. Play at any speed using a slider! * Study mode helps you learn more effectively. * Sleep timer can save your battery while you sleep. SpeedUp Player features: - Variable speed playback: 0.5X(half speed) - 2.5X (0.1X interval) - Preserve pitch(tone) while changing playback speed. - Play directly from your iPod collection. - Play from app's Documents folder. (Wi-Fi file transfer is possible) - Customizable gestures to access most features. - Configurable quick rewind/forward buttons. 4 buttons can be set individually. - Full multitasking support. - Remote controller support. - Sleep timer (pause after 10/20/30/60/120 minutes) - A/B repeat : repeat interval using simple button press - bookmark: save bookmarks with comments. A/B repeat section can be bookmarked. - reads chapter information. - Extremely fast iPod library browsing (disk+memory based cache) - Browse by album/artist/songs/playlists/podcasts - Simple playlist - Pause/resume on phone call(audio interruption). - Pause when headphone is unplugged. - Music tracks can be set to be played at 1X. - UI supports light/dark theme. - supports CarPlay. - supports lyrics (ID3 USLT/SYLT and lrc) Limitations: - video tracks are not supported. - does not support DRM protected files.
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
React Navigation
expo-av
Redux
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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.
