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
Big Ben
During 2009, the UK Parliament celebrated the 150th anniversary of its world famous Clock Tower, Great Clock and Great Bell.
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.8
38 ratings · Top 50%
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 included15 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 Big Ben: map the core Entertainment 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
Add customizable clock faces and sounds.
Assumption to check: Limited features compared to other clock apps
Validate with people who use this workflow before building.
Hypothesis 2
Implement adaptive bitrate streaming for sounds.
Assumption to check: Inconsistent sound playback quality
Validate with people who use this workflow before building.
Hypothesis 3
Introduce a snooze feature for alarms.
Assumption to check: No snooze option for alarms
Validate with people who use this workflow before building.
Hypothesis 4
Add social sharing features or customization options.
Assumption to check: Lack of user engagement 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
During 2009, the UK Parliament celebrated the 150th anniversary of its world famous Clock Tower, Great Clock and Great Bell. The name Big Ben is often used to describe the tower, the clock and the bell but the name was first given to the Great Bell. 1859 was the beginning for all three elements when the Clock Tower was completed, the Great Clock started on 31 May and the Great Bell’s chimes were heard for the first time on 11 July. Have your iPhone (or iPod Touch) display the time of day in style. Options include: adding a digital clock display showing a seconds hand having it make a tick-tock sound having it chime every quarter of an hour and toll on the hour (the chiming and tolling sounds will play even when the app is not open, so long as your device is not muted and you allow notifications in the General Settings for Big Ben) Pointless? Maybe. Decorative? Certainly. NB Sounds will only play through earphones on 1st gen iPod Touch. Thanks to all who left comments and suggestions for improvement. In particular to Dave, whose persistence finally motivated us to release this new version.
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
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expo-av
moment
BUILD KIT DIFFICULTY
Starter
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.
