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.
Merge and create multiple documents into one, or open a single PDF just to mark it up.
$2.99 · In-app purchases
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.
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Combine features and design from your favorite apps.
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Generating… usually about a minute.
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
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.
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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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for A4Pad – Merge, Annotate PDF: 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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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
Assumption to check: Limited document management features compared to desktop PDF tools.
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Performance issues with large PDF files.
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Inconsistent annotation tools and user experience.
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Lack of cloud storage options.
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Merge and create multiple documents into one, or open a single PDF just to mark it up. No account required. Everything stays on your iPhone or iPad. A4Pad works two ways: consolidate content from multiple sources — PDFs, scanned pages, photos, and screenshots — into one organized document, or open a single existing PDF to annotate, highlight, and mark it up directly. No merging required if that's all you need. Import everything into one notebook, arrange the pages exactly how you want, mark them up, and export a single polished PDF. **MERGE & CONVERT** • Combine PDFs, scanned pages, photos, and screenshots into a single document • Convert images to PDF automatically on export • Reorder, duplicate, and organize pages with a tap **SCAN & IMPORT** • Scan paper documents directly with your camera • Import photos and screenshots from your Photo Library or the Files app • Drop in existing PDFs — pages are merged in automatically **ANNOTATE — NOTHING IS EVER FINAL** • Draw, highlight, and mark up any page, then keep refining it whenever you like • Nothing is burned into the page until you export — go back and change your mind anytime • Full Apple Pencil support on iPad, finger-friendly on iPhone **EXPORT** • One tap to export a single, print-ready PDF • Share via Mail, Messages, AirDrop, or any app **PRIVATE BY DESIGN** • Everything stays on your device — no account, no cloud, no login • No trackers, no ads, no data collection • You're always in control of your files Organize your documents into Collections and Notebooks for a clear, consistent structure across every project — on iPhone or iPad.
Written user reviews are not shown here. Check current App Store reviews >
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
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.