# Side Project Ideas for Returning Engineers: Concrete and Doable

Source: https://www.techinterview.org/post/3233475033/side-project-ideas-returning-engineers/
Updated: 2026-05-05 · techinterview.org

"I should build a side project" is easy to say and hard to do when you are juggling a return to tech, daily life, and self-doubt about coding skills. The hardest part is picking something achievable. This post is a list of concrete project ideas, each scoped to a specific time budget, with the technical skills they showcase.

## Weekend projects (10–20 hours)

### 1. Personal CLI dashboard

A terminal command that fetches your day: weather, calendar events, RSS feeds, GitHub PRs needing review.

**Skills:** CLI design, async/await, API integration, JSON parsing.

### 2. Slack reminder bot

A bot that posts daily standup prompts to a Slack channel.

**Skills:** webhooks, scheduling, OAuth, basic backend.

### 3. URL preview service

A small API that returns a screenshot + title + description for any URL.

**Skills:** headless browsers (Puppeteer), HTTP, caching.

## One-week projects (40–60 hours)

### 4. Personal expense tracker

Web app to log expenses, categorize, and visualize. Authentication, persistence, charts.

**Skills:** full-stack, basic auth, database modeling, charts.

### 5. Recipe scaler

Given a URL or pasted recipe, scale all ingredients to a target servings count. Bonus: dietary substitutions.

**Skills:** text parsing, NLP basics, web scraping (or LLM call).

### 6. Markdown notes app with sync

Local-first markdown editor that syncs to Dropbox or your own server.

**Skills:** conflict resolution, offline-first, sync protocols, local storage.

## Two-week projects (60–100 hours)

### 7. URL shortener with analytics

Like bit.ly. Custom domains, click analytics, geo-distribution stats.

**Skills:** backend, Redis, geo IP, traffic analytics, dashboards.

### 8. Headless feature flag service

A self-hostable feature flag API. Boolean and percentage rollout flags.

**Skills:** backend, SDK design, real-time updates, multi-tenant.

### 9. RSS reader with categories

Modern RSS reader. Categorize feeds, mark as read, search.

**Skills:** RSS parsing, full-text search, sync, UX.

## Month-long projects (100–200 hours)

### 10. SaaS product with payments

Identify a real (small) need; build a SaaS that solves it. Stripe integration. Even if you only get 5 users, this is the strongest portfolio item.

**Skills:** end-to-end product engineering, payments, deployment, marketing.

### 11. Mobile app on the store

A small but useful native app. Could be a habit tracker, a hobby tool, or a niche utility.

**Skills:** Swift/Kotlin, App Store submission, iCloud/Firebase sync.

### 12. ML-powered tool

Build something using an LLM API or a small open-source model. Examples: writing assistant, summarizer, image classifier.

**Skills:** ML basics, prompt engineering, latency management, deployment.

## The "I want to learn X" project

If your goal is learning a specific stack:

- **Rust:** a small CLI tool that processes structured data

- **Go:** a microservice with health checks and graceful shutdown

- **TypeScript:** rewrite an existing JS project of yours in TS

- **React Native:** port a small web app you built to mobile

- **Kubernetes:** deploy any of the above to a real cluster

## Project completion is more important than ambition

A finished URL shortener beats a half-finished Twitter clone every time. Pick something you can ship in your available time.

## Frequently Asked Questions

### What if I get bored mid-project?

Either ship a smaller version (call it v1, write it up) or move on. Half-finished projects in public are negative signal.

### Should I open-source my projects?

Yes. Public GitHub repos are easier for recruiters to find. Even if no one stars them, they exist as evidence.

### How do I avoid over-engineering?

Set a deadline, write a one-page spec at the start, and resist refactoring until v1 ships.