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
Saturn Calendar
SATURN CALENDAR - THE CALENDAR FOR YOU & FRIENDS
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.7
67,803 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 included17 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 Saturn Calendar: map the core Productivity 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 more themes and colors for users to choose from.
Assumption to check: Limited customization options for events
Validate with people who use this workflow before building.
Hypothesis 2
Add a feature for easy management of recurring tasks and events.
Assumption to check: Difficulties in managing recurring events
Validate with people who use this workflow before building.
Hypothesis 3
Integrate push notifications for reminders on tasks and events.
Assumption to check: Lack of reminders and notifications
Validate with people who use this workflow before building.
Hypothesis 4
Simplify the UI and provide a more guided user experience.
Assumption to check: Cluttered interface with too many options
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
SATURN CALENDAR - THE CALENDAR FOR YOU & FRIENDS Saturn is a calendar for you and the people who matter most. Other calendars were designed for your work life. Saturn is different. It's built around your friends, your family, and your plans. YOUR CALENDAR • See your day at a glance — events, to-dos, and what's coming up, all in one screen. • Connect Google Calendar so everything stays in sync. JUST SAY IT • Type or say "Dinner with Dylan on Tuesday at 7" and it's on the calendar. • Add events, to-dos, and reminders using text or voice. • We help figure out the details and get invites out so you can go from idea to event faster. COMPARE CALENDARS • See when your friends and family are free — without their email. • No more texting "when are you free?" Just look. • Find overlapping availability and make a plan in seconds. SHARED CALENDARS • Create a shared calendar for a trip, a household, a rec league — anything. • Add events, invite people, and keep everyone on the same page. • One shared source of truth, no group chat required. THE CALENDAR FOR SNAPCHATTERS • Connect your Snap and your friends, birthdays, and Bitmojis are already here. • Snapchat and Saturn are better together. THE CALENDAR FOR STUDENTS • Rotating periods, block schedules, A/B days, lunch waves, advisory, flex blocks — Saturn handles your school's format automatically. • Already in over 20,000 US high schools, so your bell schedule could be ready to go. • Bring it to college — Saturn grows with you from your first semester through graduation.
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
@react-native-paper
Zustand
BUILD KIT DIFFICULTY
Expert
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.
