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
Serial Killer Murder Library
"This app is by FAR the BEST serial killer app hands down!" - serialkillersink.net
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.0
6 ratings · Top 30%
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 included16 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 Serial Killer Murder Library: map the core Reference 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
Implement a user feedback system for updates.
Assumption to check: Limited information updates on serial killers.
Validate with people who use this workflow before building.
Hypothesis 2
Enhance navigation with related links.
Assumption to check: Difficult navigation between detailed profiles.
Validate with people who use this workflow before building.
Hypothesis 3
Add videos and audio descriptions.
Assumption to check: No multimedia content to engage users.
Validate with people who use this workflow before building.
Hypothesis 4
Allow user contributions to validate information.
Assumption to check: Certain data may be outdated or inaccurate.
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
"This app is by FAR the BEST serial killer app hands down!" - serialkillersink.net Do you have a taste for the disturbed? Do you love the psychology of the sociopath? Every serial killer you could imagine can now be in the palm of your hand. From Bundy to Dahmer, with every killer in between, browse over 600 serial killers throughout history. 5 Stars "Well organized. Great interface. Beats anything online." - by Adrizzzz 5 Stars "Phenomenally insightful and responsible application for this genre." -AnthonyMeoli Who had the most victims? Want to see only female killers? Who was the "Acid Bath Murderer" or who was known as "Alligator Man". Browse over 175 films and TV shows based on serial killers. Discover video you had never heard of. - Share the latest serial killer news - Over 600 killers from 50 countries - Over 175 film/tv references - Sort by number of victims, gender, country and nickname - Share anything on Facebook, Twitter, Email, Camera Roll If you love this app, please take the time to rate it and help spread the word! * Internet connection required to load images. However, you will still be able to browse killers without a connection Attribution for App Previews: "Evening of Chaos" Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 3.0 http://creativecommons.org/licenses/by/3.0/
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
Supabase
React Navigation
Zustand
React Native Reanimated
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.
