Frontend · Intermediate · 2 weeks
Accessible Design System & Component Library
A themeable library of accessible UI components (dialog, combobox, tabs, data table, toast) published to npm, with a documentation site where people can try every component live.
- React
- TypeScript
- Storybook
- Vitest
- Testing Library
- axe-core
Features
- 8–10 components with full keyboard support and correct ARIA roles
- Light and dark theming driven by design tokens
- Docs site with a live props playground for each component
- Automated accessibility tests that run in CI on every pull request
- Versioned releases to npm with a generated changelog
Bonus: Visual regression testing with Playwright screenshots that block a PR if any component changes unexpectedly.
Frontend · Intermediate · 1–2 weeks
Git Repo Time-Lapse Visualizer
Paste any public GitHub repository and watch its file tree grow over time as an animated treemap, with contributor activity and the files that change most often.
- TypeScript
- Vite
- D3.js
- GitHub REST API
- Web Workers
Features
- Fetch and cache commit history with pagination and rate-limit handling
- Animated treemap playback with a timeline scrubber
- Contributor timeline and a churn heatmap of hot-spot files
- Heavy parsing moved into a Web Worker to keep animation smooth
- Shareable URLs that encode the repo and timestamp
Bonus: Export the playback as a WebM or GIF that people can drop straight into their own README.
Frontend · Intermediate · 2 weeks
Browser Logic Circuit Simulator
Drag gates, wires, clocks, and LEDs onto a canvas and watch signals propagate in real time. Build anything from a half adder to a tiny CPU in the browser.
- TypeScript
- Canvas 2D or SVG
- Vite
- Web Workers
- Vitest
Features
- Drag-and-drop gates, switches, clocks, LEDs, and seven-segment displays
- Event-driven simulation with propagation delay
- Truth-table generator for any selected circuit
- Reusable custom components built from sub-circuits
- Save, load, and share circuits by link
Bonus: A waveform timing-diagram viewer that works like a logic analyzer for any wire you probe.
Backend · Advanced · 2–3 weeks
Distributed Background Job Queue
A Redis-backed job system with multiple workers, retries, scheduled jobs, and a dead-letter queue, plus a small dashboard showing what's running and what failed.
- Go
- Redis
- PostgreSQL
- Docker Compose
- Prometheus
Features
- Enqueue API with priorities and delayed jobs
- Exponential-backoff retries and a dead-letter queue
- Horizontally scalable workers with graceful shutdown
- Idempotency keys that prevent duplicate processing
- Metrics endpoint for throughput, latency, and failure rate
Bonus: A chaos test script that kills workers mid-job and proves, with logs, that no job is ever lost.
Backend · Intermediate · 1–2 weeks
Webhook Relay & Replay Service
Receives webhooks from services like Stripe or GitHub, verifies their signatures, stores them, and forwards them reliably to your apps with retries and one-click replay.
- Node.js
- TypeScript
- Fastify
- PostgreSQL
- BullMQ
- OpenAPI
Features
- Per-source HMAC signature verification
- Durable storage with a searchable delivery log
- Retries with backoff and a per-endpoint circuit breaker
- Replay any stored event to any endpoint
- OpenAPI spec with generated API docs
Bonus: A small CLI that tunnels live events to localhost so developers can test webhooks on their own machine.
Backend · Advanced · 2 weeks
API Gateway with Rate Limiting
A reverse proxy that sits in front of your services and handles authentication, rate limiting, caching, and request logging so the services don't have to.
Features
- Config-driven routing to multiple upstream services
- Token-bucket rate limiting per API key, shared across instances through Redis
- JWT validation and API key management
- Response caching with TTLs and manual invalidation
- Structured access logs and latency metrics
Bonus: k6 load tests that publish p50, p95, and p99 latency with and without the gateway in front.
Security · Intermediate · 1–2 weeks
Git Secrets Scanner & GitHub Action
A CLI and GitHub Action that scans repositories, including full commit history, for leaked API keys, passwords, and private keys.
- Go
- Regex + entropy analysis
- GitHub Actions
- SARIF
Features
- Pattern and entropy-based secret detection
- Fast scanning of the full Git history
- Allowlist file to suppress false positives
- SARIF output that shows up in GitHub code scanning
- Pre-commit hook mode that blocks leaks before they happen
Bonus: A seeded test corpus that reports precision and recall, compared against an existing open-source scanner.
Security · Intermediate · 1–2 weeks
SSH Honeypot with Attack Dashboard
A fake SSH server on a cheap cloud VM that records the logins and commands real attackers try, shown on a live dashboard.
- Python (asyncssh) or Go
- Docker
- PostgreSQL
- Grafana
- GeoLite2
Features
- Fake shell that imitates a Linux machine and logs every command
- Analytics on the most common passwords and commands
- World map of where attempts come from
- Strong isolation: its own VM, a container, and no outbound network
- Automatically generated weekly threat summary
Bonus: A write-up analyzing one week of real attack data, published alongside the repo.
Security · Advanced · 2 weeks
End-to-End Encrypted File Sharing
Share files by link, with encryption done in the browser so the server never sees file contents or keys.
- TypeScript
- Web Crypto API
- Node.js or Go
- S3-compatible storage
Features
- AES-GCM encryption in the browser, with the key kept only in the URL fragment
- Chunked streaming encryption for large files
- Links that expire or stop after a set number of downloads
- Optional password protection with proper key derivation
- A written threat model in the README
Bonus: A verification page that shows the stored ciphertext is unreadable without the link.