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.
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.