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.
Paperback is a fast, fully accessible reader for ebooks, documents and audio books
$19.99
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.
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Combine features and design from your favorite apps.
Your first Build Kit is free with a verified email.
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 Paperback Mobile: map the core Books workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Paperback is a fast, fully accessible reader for ebooks, documents and audio books. It opens over twenty formats and speaks fifteen languages. Paperback has two ways to read a document. In text mode, you read the text with your screen reader. In read aloud mode, Paperback reads the text to you with the voice you pick in Settings, and keeps going in the background and from the lock screen. Switch between them from the More Options menu. Audio books, like DAISY, M4B, and MP3 books, play their own recording instead. The reading bar The bar at the bottom of the screen has, from left to right: • The navigation unit, such as paragraph, heading, page, or link. Swipe up or down on it to change it. • Previous, play, and next buttons. Previous and next move by the navigation unit. • The speech rate. Swipe up or down on it to change how fast Paperback reads. You can also swipe up or down on the play button to move by the navigation unit, without reaching for the previous and next buttons. If that is all you use, the Hide previous and next buttons setting takes them out of your screen reader’s way. The Swipe up moves forward setting picks which way a swipe goes. The More Options menu is where everything else lives. • Switch to TTS Mode or Switch to Text Mode: moves between read aloud mode and text mode, described above. In text mode, a Read Aloud item starts and pauses reading aloud without leaving text mode. • Table of Contents: the book’s chapters, opened at the one you’re reading. Pick one to go straight to it. Entries with chapters under them can be expanded and collapsed with VoiceOver actions. • Elements: a list of the document’s headings or links. Switch between the two with the Type picker, then pick one to go to it. • Find: type what to look for, or pick an earlier search from Search History, and choose whether to match case, match whole words only, or use a regular expression. Find Previous and Find Next jump to a match and say where it landed, and Find stays open so you can keep going. In read aloud mode, Find also shows up as a navigation unit on the reading bar, so you can step through the matches from there too. • Go To: jump to a line, a page, or a percentage through the document. Pick which with the Mode picker. • Recent Documents: every document you’ve opened, each marked as currently open, closed, or file missing. Each one has two VoiceOver actions: Remove takes it off the list, and Locate lets you find a document whose file has moved. Clear Recent Documents empties the list without deleting any documents. • Word Count: the number of words in the document. • Document Info: the title, the author, the file name, and the line and character counts. • Export: saves the document as plain text, HTML, or Markdown. • Sleep Timer: stops reading after 5, 10, 15, 30, 45, or 60 minutes, or a time of your own. Open it again while it’s running to see how long is left, or to cancel it. • Help: opens the readme. • Settings: ◦ Text to speech: the voice, speech rate, and pitch, a Play Sample button to hear them, and the pause between paragraphs. This is also where the speech dictionary is: rules that change how words are spoken, for every voice or just some. ◦ Readability: text size, line spacing, paragraph spacing, alignment, and high contrast text, as well as light and dark appearance. ◦ Behavior: whether to reopen your documents when the app starts, which way a swipe on the play button moves, and whether to hide the previous and next buttons.
Written user reviews are not shown here. Check current App Store reviews >
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 book discovery features
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: No social features for sharing reviews
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Lack of personalized recommendations
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Missing offline access to library
Validate with people who use this workflow before building.
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.
Not assessed in a Build Kit yet.
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.