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
Interesting Engineering
Trusted by 25M+ readers for in-depth science, technology, and engineering journalism
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.7
80 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.
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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/
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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 Interesting Engineering: map the core News 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 an ad-free premium subscription tier.
Assumption to check: Ads can be intrusive and decrease user engagement
Validate with people who use this workflow before building.
Hypothesis 2
Integrate a personalized feed algorithm based on user preferences.
Assumption to check: Limited personalization of news feed
Validate with people who use this workflow before building.
Hypothesis 3
Include offline reading capabilities for saved articles.
Assumption to check: Lack of offline reading features
Validate with people who use this workflow before building.
Hypothesis 4
Add text-to-speech functionality for accessibility.
Assumption to check: No text-to-speech options for articles
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
Trusted by 25M+ readers for in-depth science, technology, and engineering journalism. Subscribe to unlock unlimited access to articles, podcasts, and exclusive reporting from the frontiers of innovation. Interesting Engineering is the leading source for science news, tech news, and engineering breakthroughs - from AI and robotics to space and clean energy - covering the discoveries and innovations shaping our future. The app is free to download - browse listing pages and preview headlines at no cost. Subscribe for full access to all content. WHAT YOU GET WITH A SUBSCRIPTION: - Unlimited access to all IE articles and videos - Premium interviews with researchers, founders, and engineers - Exclusive podcasts and audio content - Daily quizzes - Clean, ad-free reading experience WHAT WE COVER - Artificial intelligence (AI) and emerging tech - Robotics, defense, and biotech - Renewable energy and climate innovation - Space exploration and aerospace - Engineering breakthroughs and scientific research BUILT FOR: Engineers, researchers, students, and anyone curious about how the world of engineering works. SUBSCRIPTION OPTIONS - Monthly: $4.99 - Annual: $52.99 Payment will be charged to your Apple ID account at confirmation of purchase. Subscriptions automatically renew unless auto-renew is turned off at least 24 hours before the end of the current period. Your account will be charged for renewal within 24 hours prior to the end of the current period at the cost of the chosen package. You can manage and cancel your subscriptions by going to your App Store account settings after purchase. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Policies: https://interestingengineering.com/policies
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
Zustand
React Navigation
Axios
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.
