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.
Full-stack · Advanced · 2–3 weeks
Real-time Collaborative Whiteboard
A multiplayer canvas where several people draw, add sticky notes, and see each other's cursors live, with edits that never conflict.
- React
- TypeScript
- Yjs (CRDT)
- WebSockets
- Node.js
- PostgreSQL
Features
- Shapes, freehand drawing, and sticky notes
- Live cursors and presence indicators
- Conflict-free merging of simultaneous edits using CRDTs
- Shareable boards with view-only and edit links
- Persistent boards with version history
Bonus: Offline editing that merges cleanly with everyone else's changes when you reconnect.
Full-stack · Advanced · 2–3 weeks
Live Coding Interview Room
Create a room, share a link, and code together in a shared editor. Code runs in sandboxed containers and both people see the output.
- Next.js
- Monaco Editor
- WebSockets
- Docker
- Redis
Features
- Shared editor with synced cursors and selections
- Run Python, JavaScript, or C++ in isolated containers with CPU, memory, and time limits
- Private notes panel only the interviewer can see
- Session playback of the whole interview
- Rooms that expire and clean up automatically
Bonus: Hidden test cases that grade the candidate's solution automatically and show a pass/fail report.
Full-stack · Intermediate · 2 weeks
Uptime Monitor & Public Status Page
Monitors websites and APIs every minute, detects outages, opens incidents, and publishes a clean public status page with uptime history.
- Next.js
- TypeScript
- PostgreSQL
- Node.js worker
- Email or Discord webhooks
Features
- HTTP, TCP, and keyword checks run on a schedule by a worker
- Incident detection that confirms with retries to avoid false alarms
- 90-day uptime bars and response-time charts
- Email and Discord alerts when something goes down
- Admin page for posting incident updates
Bonus: Checks from two regions that only open an incident when both agree the service is down.
Mobile · Intermediate · 2–3 weeks
Offline-first Field Inspection App
A mobile app for technicians who inspect equipment on site: checklists, photos, and signatures that work with no signal and sync later.
- React Native (Expo)
- TypeScript
- SQLite
- Supabase
Features
- Dynamic checklist templates loaded from the server
- Photo capture with on-image annotation
- Local-first storage with background sync and conflict handling
- Signature capture and PDF report export
- GPS-tagged inspections
Bonus: A small web admin dashboard where managers create templates and review submitted inspections.
Mobile · Intermediate · 2 weeks
Bluetooth LE Sensor Companion App
A phone app that discovers a Bluetooth Low Energy sensor, streams live readings, keeps a history, and sends settings back to the device.
- Flutter (Dart)
- flutter_blue_plus
- SQLite
- ESP32 or nRF52 as the peripheral
Features
- Scan, connect, and auto-reconnect to the device
- A custom GATT service and characteristics that you define
- Live charts of incoming readings
- Local history with CSV export
- Write settings like sample rate and thresholds back to the device
Bonus: Firmware updates delivered over Bluetooth straight from the app.
DevOps & Cloud · Advanced · 2–3 weeks
GitOps Kubernetes Home Lab
A fully automated Kubernetes cluster where pushing to Git builds, scans, and deploys your apps, with monitoring and alerts built in.
- Terraform
- k3s
- Argo CD
- Helm
- Prometheus
- Grafana
- GitHub Actions
Features
- Infrastructure as code for all VMs or cloud instances
- CI pipeline that builds, scans, and pushes container images
- Argo CD auto-sync from a Git repository
- Grafana dashboards and alert rules
- Secrets managed safely with Sealed Secrets
Bonus: Canary rollouts that roll back automatically when the error rate spikes.
DevOps & Cloud · Intermediate · 1–2 weeks
Distributed Tracing Playground
Three small microservices instrumented end to end, so you can follow a single request across every service with linked logs, metrics, and traces.
- OpenTelemetry
- Docker Compose
- Jaeger or Tempo
- Prometheus
- Grafana
- Loki
Features
- Three services in two languages, instrumented with OpenTelemetry
- Trace context carried through HTTP calls and a message queue
- Dashboards for rate, errors, and duration
- Logs linked to their trace IDs
- SLOs with burn-rate alerts
Bonus: A fault-injection switch that adds latency or errors so viewers can see exactly how problems show up.
DevOps & Cloud · Intermediate · 1–2 weeks
Serverless Media Pipeline on AWS
Upload an image or video and an event-driven pipeline resizes, transcodes, and tags it automatically. All infrastructure is defined in code.
- AWS S3, Lambda, SQS, DynamoDB
- AWS CDK or Terraform
- TypeScript or Python
- GitHub Actions
Features
- Direct uploads using presigned URLs
- S3 events feeding SQS and Lambda, with retries and a dead-letter queue
- Thumbnails and metadata stored in DynamoDB
- Least-privilege IAM roles for every function
- CI/CD that deploys separate dev and prod stages on merge
Bonus: A cost report in the README showing the real cost per 1,000 uploads.
Systems · Advanced · 2–3 weeks
LSM-Tree Key-Value Store
A persistent key-value database built from scratch with a write-ahead log, memtable, SSTables, and compaction, like a tiny RocksDB.
- Rust or C++
- TCP
- criterion / Google Benchmark
Features
- Write-ahead log with crash recovery
- Memtable flushed to sorted SSTable files
- Bloom filters to skip unnecessary disk reads
- Background compaction
- Simple TCP protocol with a CLI client
Bonus: Benchmarks against SQLite with throughput and latency graphs in the README.
Systems · Advanced · 2–3 weeks
RISC-V Emulator with Debugger
An RV32I CPU emulator that runs real programs compiled with GCC, plus a step debugger for registers and memory.
- C++ or Rust
- RISC-V GCC toolchain
- SDL2 (optional)
Features
- Fetch, decode, and execute for the full RV32I instruction set
- ELF loader for compiled binaries
- Memory-mapped UART so programs can print
- Step debugger with register and memory views
- Passes the official riscv-tests suite
Bonus: A 5-stage pipeline view that visualizes hazards, stalls, and forwarding cycle by cycle.
Systems · Advanced · 2–3 weeks
Mini Container Runtime
Your own version of docker run, built from scratch: isolated processes with their own filesystem, process tree, network, and resource limits.
- Go or C
- Linux namespaces
- cgroups v2
- OverlayFS
Features
- PID, mount, UTS, and network namespaces
- Root filesystem set up with pivot_root from an image tarball
- CPU and memory limits using cgroups v2
- Layered filesystems with OverlayFS
- veth networking so containers can reach the internet
Bonus: Pull and run real images from Docker Hub by implementing the registry API.
Systems · Advanced · 2–3 weeks
Compiler for a Small Language
A compiler for your own small language, with variables, functions, loops, and structs, that outputs WebAssembly or x86-64 assembly and runs real programs.
- Rust, C++, or OCaml
- WebAssembly (WAT) or x86-64
- A test harness
Features
- Hand-written lexer and recursive-descent parser
- Type checker with clear error messages that point at the source
- An intermediate representation with constant folding and dead-code elimination
- Code generation to WebAssembly or assembly
- Test suite of example programs with expected output
Bonus: A web playground that compiles and runs programs right in the browser.
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.
Games · Advanced · 2–3 weeks
Multiplayer Arena with Real Netcode
A fast top-down browser arena game with an authoritative server, client-side prediction, and lag compensation, so it feels smooth even at 150 ms ping.
- TypeScript
- HTML Canvas or Phaser
- Node.js
- WebSockets
Features
- Authoritative server running at a fixed tick rate
- Client-side prediction with server reconciliation
- Entity interpolation for other players
- Lobby and simple matchmaking
- Built-in network simulator with latency and packet-loss sliders
Bonus: A replay system that records inputs and plays back any match deterministically.
Games · Intermediate · 2–3 weeks
Procedural Roguelike with ECS
A turn-based dungeon crawler with procedurally generated levels, built on an entity-component-system architecture.
- Rust + Bevy
- or C# + Godot
- WebAssembly build
Features
- Seeded dungeon generation using BSP or cellular automata
- Entity-component-system architecture for all game objects
- Field of view and A* pathfinding for enemies
- Items, inventory, and save/load
- A playable web build published on itch.io
Bonus: A daily seeded challenge where everyone plays the same dungeon.