Not Plain Calc

Not Plain Calc v1.0 is a polished offline calculator built with Expo and React Native. It keeps the familiar speed of a standard calculator while giving the product a softer, more intentional utility feeling.

Hero Description

A calculator does not need to look generic to feel reliable. Not Plain Calc combines precise arithmetic flows, tactile controls, responsive typography, accessibility-minded interaction states, and restrained motion into a small iOS-first product that feels calm, structured, and carefully finished.

Release Status

Not Plain Calc v1.0 is prepared as a public GitHub release and TestFlight-ready build candidate. It is not yet submitted to Apple. Final TestFlight and App Store submission still require human setup for Apple Developer credentials, App Store Connect metadata, support/marketing URLs, and Apple privacy labels.

Design Philosophy: Friendly Precision

Friendly Precision is the visual and interaction direction behind the app:

• Friendly: warm platinum surfaces, tactile squircle controls, gentle depth, readable hierarchy, and haptics that support the action instead of calling attention to themselves.
• Precision: strict input limits, predictable operator behavior, accessible labels, compact-screen adaptation, and display formatting that protects legibility.
• Not plain: small visual details such as the blue operator rail, coral equals key, result well, active operator state, and press depth give the app a memorable identity without changing the expected calculator mental model.

Design Exploration

The final production design, Macintosh Refined, was inspired by the friendliness, clarity, and structured interaction philosophy of early personal-computer interfaces. It is an original reinterpretation for a modern mobile calculator: it is not a copy, not an emulator, not a recreation of a Macintosh window or calculator, and does not use Apple logos, Apple-owned artwork, or copyrighted Macintosh imagery.

Not Plain Calc is independent and is not affiliated with, endorsed by, or sponsored by Apple Inc.

Privacy-First Offline App

Not Plain Calc is a local calculator:

• No login
• No user accounts
• No backend
• No database
• No analytics
• No ads
• No tracking
• No personal data collection
• No calculator input leaves the device

Features

• Standard calculator operations: add, subtract, multiply, divide, equals, percent, decimal input, clear, and delete.
• Responsive iPhone layout with compact-screen adjustments.
• Active operator state for clearer multi-step calculations.
• Animated press states and result resolution feedback with reduced-motion support.
• Native haptic feedback for number, utility, operator, and equals interactions.
• Accessible button labels and result announcements.
• Focused unit tests for arithmetic, formatting, and calculator state transitions.
• Centralized design tokens for color, spacing, typography, motion, shadows, radius, and layout.

Tech Stack

• Expo 54
• React 19
• React Native 0.81
• Expo Router
• TypeScript
• React Native Reanimated
• React Native Gesture Handler
• Expo Haptics
• Vitest

Architecture

The project separates routing, interface components, design tokens, haptics, and calculator logic:

• app/ contains Expo Router entry points.
• src/components/calculator/ contains the visible calculator UI.
• src/design-system/tokens/ contains reusable visual system primitives.
• src/haptics/ isolates native feedback behavior.
• src/logic/calculator/ contains calculation, formatting, types, and state-machine logic.

This keeps visual polish independent from calculator behavior, making the code easier to review and safer to extend.

Folder Structure

.
├── app/
│   ├── _layout.tsx
│   └── index.tsx
├── assets/
│   └── icon.png
├── src/
│   ├── components/
│   │   └── calculator/
│   ├── design-system/
│   │   └── tokens/
│   ├── haptics/
│   └── logic/
│       └── calculator/
├── app.json
├── babel.config.js
├── package-lock.json
├── package.json
└── tsconfig.json

Installation

Install dependencies from the project root:

npm install

Running Locally

Start the Expo development server:

npm start

Run on iOS:

npm run ios

Run type checking:

npm run typecheck

Run unit tests:

npm test

Validate Expo package compatibility:

npx expo install --check

Release Assets

• Release audit: docs/release-audit.md
• Privacy policy draft: docs/privacy-policy.md
• App Store metadata draft: docs/app-store-metadata.md
• TestFlight readiness: docs/testflight-readiness.md
• GitHub Pages setup: docs/github-pages.md
• Public pages source: docs/index.html, docs/privacy.html, docs/support.html
• App Store screenshots: docs/screenshots/app-store/

Roadmap

• Configure Apple Developer credentials for TestFlight.
• Create the App Store Connect record and upload screenshots.
• Explore optional v2 interactions only after the v1 release is fully locked.

Lessons Learned

• A small utility app benefits from a real design system; tokens made the visual polish consistent without scattering magic values.
• Calculator UX depends on predictable state transitions more than on visual novelty.
• Motion and haptics feel best when they confirm intent quietly.
• Compact-device support is easier when layout constraints are named and centralized early.
• Portfolio-quality work is not only the final screen; it is also clear structure, readable architecture, and disciplined scope control.