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
MP3 Converter -Audio Extractor
MP3 Converter converts any video to MP3 audio and saves it on your phone so you can listen to it anytime and anywhere.
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.7
47,713 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.
Build your own version
Build Kit
Make this idea yours
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Add to a Remix
Combine features and design from your favorite apps.
Kit ready. Verify your email to download it.
Generating… usually about a minute.
Make it yours Optional
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included18 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.
JavaScript is required to complete mailbox verification.
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 MP3 Converter -Audio Extractor: map the core Music workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
Preview ready. Verify your email to reveal and copy the full prompt.
JavaScript is required to complete mailbox verification. Return to this prompt preview.
Continue in Rork >
Affiliate link: CloneChart may earn a commission at no extra cost
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 more free trials or features to engage users.
Assumption to check: Limited free conversions before paywall
Validate with people who use this workflow before building.
Hypothesis 2
Support more audio formats for conversion.
Assumption to check: File format limitations
Validate with people who use this workflow before building.
Hypothesis 3
Optimize conversion algorithms for faster processing.
Assumption to check: Slow conversion times reported
Validate with people who use this workflow before building.
Hypothesis 4
Implement a cohesive design system for a unified look.
Assumption to check: Inconsistent user interface across screens
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
MP3 Converter converts any video to MP3 audio and saves it on your phone so you can listen to it anytime and anywhere. Features: - Convert video to MP3. - Very fast and easy to use. - Supports most video formats. - Supports most audio formats. - Widget to quickly import video or play recent audio - Multiple audio clippers and splicers - Intelligent denoising function - Audio post-processing (voice removal, equalizer, bass enhancement, automatic gain, etc.) - Quickly set ringtones - Share your mp3 files via other apps. ========================== MP3 Converter Pro Unlimited Subscription ========================== - MP3 Converter Pro Unlimited use all features for free, including more format support, unlimited timelimit, richer import and export modes, and ads are automatically removed. - MP3 Converter Pro Unlimited subscription is billed annually at the rate correspnding to the selected plan. In addition, a one-time payment will be offered if needed, which is not one of the subscription plan. - Payment will be charged to Itunes Account at confirmation of purchase. - Subscriptions automatically renews unless auto-renew is turned off at least 24 hours before the end of the current period. - Account will be charged for renewal within 24-hours prior to the end of the current period, and identify the cost of the renewal. - Subscriptions may be managed by the user and auto-renewal may be turned off by going to the user's Account Settings after purchase. - Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that publication, where applicable. - Terms of use: https://vl2d7p74tu.feishu.cn/docx/Ma7xdszymo8gpDxBJbGcV0YCnab - Privacy Policy: https://vl2d7p74tu.feishu.cn/docx/HcHHdXlnvoV6sOxKl4ccErZYnr4 Feel free to contact us: [email protected] Your problems or suggestions are important to us!
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
< Scroll to see more >
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
Expo File System
Zustand
BUILD KIT DIFFICULTY
Advanced
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.
