Build projects
Two strong projects beat six basic CRUD projects. Put the architecture in the README so you can talk about it.
Beginner
Ship a running API and auth. That's the bar.
REST API
What to build. A small JSON API with CRUD for one resource (notes or todos), validation, and clear status codes.
Skills. HTTP · REST · Express/Spring · JSON
Suggested stack. Node.js + Express · or Java + Spring Boot
Authentication system
What to build. Register, login, logout, protected routes. Prefer sessions or a well-understood JWT flow — and be able to explain the tradeoff.
Skills. Sessions · Cookies · Password hashing · Auth middleware
Suggested stack. Next.js + Auth.js · or Express + sessions
Blog backend
What to build. Posts, authors, comments. Relational schema with foreign keys. Pagination.
Skills. SQL schema · Joins · CRUD
Suggested stack. PostgreSQL · Express or Spring
Expense tracker
What to build. Categories, monthly totals, simple charts. Good first full-stack project if you also add a tiny UI.
Skills. Aggregations · REST · Basic UI
Suggested stack. PostgreSQL · any web framework
Intermediate
Pick one or two. Depth beats six CRUD clones.
E-commerce backend
What to build. Catalog, cart, orders, inventory decrement. Think about what happens if two people buy the last item.
Skills. Transactions · Schema design · Idempotency
Suggested stack. PostgreSQL · Node or Java
Chat application
What to build. 1:1 messages over WebSockets. Delivery status if you have time.
Skills. WebSockets · Realtime · Auth
Suggested stack. Socket.IO + Node
URL shortener
What to build. Create short links, redirect, click counts. Unique codes. This also prepares you for the HLD version.
Skills. Hashing · Redirects · Simple analytics
Suggested stack. Any backend + Redis optional
Job portal
What to build. Job listings, apply, search/filter. Roles: candidate vs recruiter.
Skills. Authz · Search · Relational modeling
Suggested stack. PostgreSQL · Express/Spring
Notification system
What to build. Queue an event, send email or in-app notification. Retry on failure.
Skills. Queues · Retries · Idempotency
Suggested stack. Node + a queue (BullMQ/Redis)
Advanced
Only after you can defend an intermediate project in an interview.
Scalable URL shortener
What to build. Same product as the intermediate shortener, plus caching, unique ID generation, and a write-up of how it would scale.
Skills. Caching · ID generation · Read-heavy systems
Suggested stack. API + Redis + Postgres
Real-time chat system
What to build. Rooms, presence, reconnect. Document how you'd shard connections later.
Skills. WebSockets at scale · Fan-out
Suggested stack. Socket.IO or similar
Distributed notification system
What to build. Multiple channels (email, push, in-app), a worker pool, dead-letter queue.
Skills. Kafka/Redis streams · Workers
Suggested stack. Kafka or Redis + workers
Social media backend
What to build. Follow graph, feed of posts. Start with pull-based feed. Write the fan-out vs pull tradeoff.
Skills. Graphs · Feeds · Pagination
Suggested stack. Postgres + Redis
Video streaming platform
What to build. Upload metadata + playback URL. You do not need to build a real CDN. Explain chunking and CDN in the README.
Skills. CDN · Object storage concepts
Suggested stack. API + object storage (S3-compatible)