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
Reverse Audio: Funny Voice
Reverse Audio: Sing Challenge is the easiest way to flip your audio, voice, or singing into a fun backwards effect
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.6
15,173 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 should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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 Reverse Audio: Funny Voice: map the core Music 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
Offer a wider variety of effects and customization options.
Assumption to check: Limited effects options compared to other audio apps
Validate with people who use this workflow before building.
Hypothesis 2
Provide an ad-free experience with a premium subscription.
Assumption to check: Free version has too many ads
Validate with people who use this workflow before building.
Hypothesis 3
Simplify the sharing process with direct integration to popular platforms.
Assumption to check: Difficult to share recordings on social media
Validate with people who use this workflow before building.
Hypothesis 4
Optimize audio processing to handle longer files without crashes.
Assumption to check: App crashes on longer recordings
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
Reverse Audio: Sing Challenge is the easiest way to flip your audio, voice, or singing into a fun backwards effect. Record any voice or sound, hit reverse, and hear your audio instantly flipped. It’s fast, entertaining, and perfect for anyone who loves playing with sound. [Reverse Singing Challenge] Try the viral reverse sing challenge: • Record your voice or sing a short line. • Play it reversed to hear the backwards version. • Sing it again following the reversed audio. • Play your new audio forward and discover the hilarious results! Perfect for creators, friends, and anyone who loves a unique voice challenge. [ Reverse Audio Features] • Reverse any audio or voice in seconds • Record and reverse voice, singing, or sound effects • Clear, fast audio processing for smooth playback • Adjust reverse speed for creative sound results • Save and share your reversed audio anywhere Whether you're trying the reverse sing challenge, creating funny voice clips, or experimenting with unique audio effects, Reverse Audio: Sing Challenge gives you a fast and fun way to transform your sound. Flip your audio, twist your voice, and enjoy endless reverse creativity with Reverse Audio: Sing Challenge. All personal data is protected in accordance with the Terms of Use and Privacy Policy: https://nexifyvn.com/privacy https://nexifyvn.com/terms
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
Axios
Zustand
expo-av
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.
