Open Calc

A simple and beautiful calculator for Android downloaded more than 300k times

Mobile App DevelopmentKotlinGPL-3.0

Abstract

Open Calc is an open-source Mobile App Development project. A simple and beautiful calculator for Android downloaded more than 300k times. It is built using Kotlin, Android. Key capabilities include: Lightweight (APK ~2MB); No unnecessary permissions; Dark, Light, Amoled and Material You theme. The complete source code is publicly available on GitHub under the GNU General Public License v3.0, making it a useful reference for students building a Mobile App Development mini project or final-year project.

1. Introduction

A simple and beautiful calculator for Android downloaded more than 300k times

2. Objective

A simple and beautiful calculator for Android downloaded more than 300k times

This project demonstrates how Kotlin, Android can be applied to a real-world Mobile App Development problem.

3. Key Features / Modules

  • Lightweight (APK ~2MB)
  • No unnecessary permissions
  • Dark, Light, Amoled and Material You theme
  • Scientific mode
  • Portrait and landscape orientation
  • Quick settings tile
  • Available on locked screen

4. Technology Stack

KotlinAndroid

5. System Requirements

General requirements for this technology stack — check the README for exact versions.

  • Android Studio (latest)
  • JDK 17
  • Android device or emulator
  • Git (to clone the repository)

6. Installation & Setup

git clone https://github.com/clementwzk/OpenCalc.git
cd OpenCalc

Full setup instructions are in the project README.

7. Future Enhancements

Suggested extensions you can add to make this your own project.

  • Add push notifications with Firebase Cloud Messaging
  • Add offline support with local caching
  • Publish an internal test build on the Play Store

8. Viva / Review Questions

Common questions examiners ask for projects in this domain.

  1. Which framework is used and why (native vs cross-platform)?
  2. How is app state managed across screens?
  3. Where is the data stored — locally, Firebase or a REST backend?
  4. How are permissions (camera, location, storage) handled?
  5. How would you publish this app to the Play Store / App Store?

9. Source Code & License

This project is developed by clementwzk and published on GitHub under the GNU General Public License v3.0. Please follow the license terms and credit the original author when you use or modify this code.

View Source on GitHubDownload ZIP

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