App Overview

A Civil Twilight icon

A Civil Twilight

JSC BIZ, LLC · Weather

A Civil Twilight shows the four solar times that define usable light:

$1.99 · In-app purchases

PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet

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.

Build your own version

Build Kit

Make this idea yours

A product spec, screen plans, and build steps for your coding agent.

First kit free with a verified email

Add to a Remix

Combine features and design from your favorite apps.

Kit ready. Verify your email to download it.

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/
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.

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.

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.

JavaScript is required to complete mailbox verification.

Free quick prompt For a smaller starting point

Quick prompt

> SELECT BUILD PLATFORM:

Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.

// RORK SYSTEM PROMPT
Rork plan preview for A Civil Twilight: map the core Weather workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
            

Preview ready. Verify your email to reveal and copy the full prompt.

JavaScript is required to complete mailbox verification. Return to this prompt preview.

Continue in Rork copies the full prompt to your clipboard first, then opens Rork in a new tab.

Continue in Rork >

Affiliate link: CloneChart may earn a commission at no extra cost

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 customizable alerts and themes.

Assumption to check: Limited user engagement due to lack of personalization

Validate with people who use this workflow before building.

Hypothesis 2

Integrate a more reliable weather API.

Assumption to check: Poor weather accuracy reported by users

Validate with people who use this workflow before building.

Hypothesis 3

Allow users to save favorites for offline access.

Assumption to check: Lack of offline functionality

Validate with people who use this workflow before building.

Hypothesis 4

Enhance radar visuals and add interactive elements.

Assumption to check: Limited radar features compared to competitors

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

A Civil Twilight shows the four solar times that define usable light: • First light — morning civil twilight begins • Sunrise — morning twilight ends • Sunset — evening twilight begins • Last light — evening civil twilight ends Glance at your watch or phone and know exactly how much light you have left — out hunting, on the water, flying, photographing, or just planning a dawn run. WHY CIVIL TWILIGHT? Civil twilight (sun within 6° below the horizon) is the standard that many hunting regulations, FAA night-flight logging rules, and boating navigation-light requirements are written around. It is also the photographer's blue hour. This app gives you those boundaries precisely, not approximately. ON YOUR IPHONE • Today's four times, front and center, on a twilight-sky backdrop • Swipe up or down to step through days; jump anywhere with the full-screen calendar • Twilight alerts: get notified 5, 30, 60 minutes — or any custom lead time — before first light or sunset • A built-in field guide: what civil twilight is, the 6° rule, the golden hour, and why these four times matter • Choose your look: Twilight, Light, Dark, or Auto ON YOUR APPLE WATCH • All four times at a glance for your exact location • Scroll through any day, ±180 days; tap the date for a calendar • The period you are in right now is highlighted • Watch-face complications: next light boundary, current solar window, and first/last light PRIVATE BY DESIGN All calculations happen on your device using standard solar math. Your location never leaves your watch or phone. No account, no ads, no tracking, no network connection required. Works anywhere on Earth, including high latitudes (where the sun may not cross a boundary on a given day, the app shows it honestly). From PresenceProof by JSC Biz LLC.

Written user reviews are not shown here. Check current App Store reviews >

Screenshots

< Scroll to see more >

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
Axios
Zustand
react-navigation
react-native-maps
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.