Pet Project in App Development — What It Is, Ideas, and Where to Start

What Is a Pet Project and Why Create One

Pet project is a software product that a developer creates in their free time for personal purposes: learning, experimentation, or automating personal tasks. Unlike at work, where technologies and architecture are often dictated by business requirements and legacy code, a pet project gives complete freedom of choice: want to try Rust for mobile development? Go ahead. Want to write your own compiler? Go for it.

Why create a pet project? The first reason is learning through practice. Theory (books, courses, documentation) provides a foundation, but real understanding comes only when you make architectural decisions yourself, fix bugs yourself, and deploy to production yourself. Learning by doing is the most effective way to master a new stack. The second reason is portfolio: an employer sees not just a line on a resume saying “know Flutter” but an actual project with architecture, tests, and CI/CD.

The third reason is career growth. A developer with a pet project can show code during an interview, talk about architectural decisions, and demonstrate an understanding of the full development cycle — from idea to deployment. According to the Stack Overflow Survey (2025), developers with public pet projects receive on average 15–20% more offers for senior positions. Pet project — not an obligation, but a career investment.

How to Choose an Idea for a Pet Project

The main mistake beginners make is starting with a “too big idea”: “I’ll write my own Instagram.” A pet project with a huge scope is doomed to be abandoned after 2–3 weeks because the developer hits complexity and loses motivation. The right strategy: choose an idea that can be turned into a working prototype in 2–4 weeks, then iteratively expand. MVP mindset — the minimum version that does exactly one thing.

The best categories for pet projects: clone an existing app on a new stack (habit tracker, password manager, weather app, RSS reader); build a tool to automate a personal task (resume parser, report generator, Telegram bot); create a library or plugin for the open-source community (a convenient API wrapper, a custom Gradle plugin, a Figma plugin). Clone project — the best start: you know how it should work, and you can focus on learning the technology rather than designing UX.

Criteria for choosing an idea: it interests you personally (if not interesting, you’ll quit in a week); achievable in 2–4 weeks to MVP; allows you to use the technology you want to learn; solves a real problem (yours or someone you know). Ideas that don’t work: yet another to-do list (millions of alternatives), crypto exchange (legal compliance), social network (huge scope). Goldilocks principle: not too simple (boring), not too complex (you’ll quit), but just right — interesting and achievable.

Choosing a Tech Stack for Your Personal Project

Choosing a stack depends on the goal of your pet project. If the goal is to learn a new technology, the stack is obvious: that very technology. If the goal is to create a useful tool, choose a stack you’re already competent in, so you don’t waste time learning syntax. Compromise: 70% familiar stack + 30% new. For example, an Android developer could use familiar Kotlin + a new architecture (MVI instead of MVVM) and a new animation library (Compose Animation).

Popular combinations for mobile pet projects: Kotlin + Jetpack Compose (Android); Swift + SwiftUI (iOS); Flutter + Dart (cross-platform); React Native + TypeScript (cross-platform). For backend: Kotlin + Ktor (lightweight server), Go + Chi (high performance), Python + FastAPI (rapid prototyping). Full-stack pet project can include a mobile client + backend + database + CI/CD — giving you an understanding of the full development cycle.

An important tip: don’t try to make the perfect stack choice at the start. Choose what interests you right now. If in a month you realize the stack isn’t right — rewrite the project in another one. The rewrite experience is also valuable. In a pet project, there’s no technical debt except what you create for yourself. Freedom of choice is the main advantage of a pet project over commercial development.

How to Organize the Process and Not Abandon Your Project

80% of pet projects are abandoned within the first 3 months. The reason is not lack of time but poor organization. The main enemies: no deadline (can be postponed forever), too large a scope (demotivation from endless work), perfectionism (wanting to make it perfect the first time). Anti-patterns: “I’ll study all the documentation first, then start writing code” — wrong. Start writing code from day one, using documentation as a reference.

Practical tips for maintaining momentum: set a regular time for your project (e.g., every Tuesday and Thursday from 8:00 PM to 10:00 PM), make small commits with clear messages (this gives a sense of progress), use GitHub Issues or a simple to-do list to plan next steps, deploy early (Firebase Hosting, Vercel, GitHub Pages) to see the result live. Ship early, ship often — a principle that works for pet projects too.

If you miss a week — don’t blame yourself and don’t try to catch up over the weekend. Just return to your regular schedule. A pet project shouldn’t become a source of stress. If the project stops bringing joy — you can set it aside or close it. Sunsetting (consciously ending a project) is a normal practice. The main thing is to learn the lessons and, perhaps, publish the code as a reference.

How to Turn a Pet Project into a Career Asset

Just writing code and forgetting about it is not enough. For a pet project to boost your career, it needs to be presentable. A quality README is the first thing a recruiter or tech lead will see on GitHub. The README should contain: a project description (what and why), screenshots or a GIF demo, setup instructions, an architectural overview (patterns, libraries, approaches), and a link to a live demo (if applicable). README first impression — a developer’s business card.

Additional elements that increase portfolio value: CI/CD pipeline (a GitHub Actions badge in the README shows the project is maintained); unit tests and UI tests (demonstrate understanding of testing best practices); architecture documentation (ADRs, diagrams); issues and PRs with discussions (show the ability to work in a team even on a personal project). Quality signals for recruiters: tests + CI + README + structure > number of stars or commits.

How to mention a pet project on your resume: a separate “Personal Projects” section with 2–4 projects. For each: name, GitHub link, tech stack, 2–3 sentences about the problem and solution. If the project has active users (friends, family) or is published on a store — be sure to mention the number of installs/downloads. Metrics: “Flutter pet project, 50+ installs on Google Play, CI/CD via GitHub Actions, 85% test coverage” says more than “know Flutter”.

<!-- Example Personal Projects section in resume -->

## Personal Projects

### BudgetTracker — [GitHub](https://github.com/username/budget)
Stack: Kotlin, Jetpack Compose, Room, Ktor Client
Personal budgeting app with offline-first architecture.
- MVVM + Clean Architecture, 80% test coverage
- Published on Google Play, 200+ installs
- CI/CD via GitHub Actions + Fastlane

### WeatherBot — [GitHub](https://github.com/username/weatherbot)
Stack: Python, FastAPI, Telegram Bot API, Redis
Weather notification bot with location-based forecasts.
- Async processing via Celery + Redis
- Deployed on Railway with 99.9% uptime

Important: don’t turn your pet project section into a dump of 20 abandoned repositories. Choose 2–3 best ones where the code is clean, the README is complete, and tests pass. Curated portfolio is worth more than quantity.

When a Pet Project Becomes an Open-Source Project

Not every pet project needs to be open-source. If the project solves a personal problem and is unlikely to be useful to others — a private repository is perfectly fine. But if the project implements functionality that other developers are looking for (library, plugin, tool), it’s worth publishing publicly. Open-source adds visibility, community feedback, and builds reputation in the developer community.

Key elements of an open-source pet project: a license (MIT, Apache 2.0 — the most common); CONTRIBUTING.md (how to contribute); issue templates (bug report, feature request); code of conduct; semantic versioning with release tags. Without these elements, the project looks like an unfinished personal experiment rather than an open-source project. Barrier to entry: a good open-source project takes more time on maintenance (reviewing PRs, answering issues) than on writing code.

Success stories of open-source pet projects: Retrofit (Square), Picasso, Coil — all started as pet projects by developers solving their own pain. Picasso (image loading for Android) was written by Jake Wharton over a weekend as a solution to a problem, and now it’s used by millions of apps. Pet to product — the journey from a personal project to an industry standard is possible but shouldn’t be the end goal.