Backend Project Ideas

Build a RESTful API that lets users log and categorize personal expenses with full CRUD operations.

• Implement GET, POST, PUT, DELETE endpoints for expenses
• Store data in a relational database (SQLite or PostgreSQL)
• Filter expenses by date range and category via query params
• Return meaningful HTTP status codes and JSON error messages
• Validate request bodies and reject malformed input

Create a standalone auth service with registration, login, and JWT-protected routes.

• Register and login endpoints with hashed passwords (bcrypt)
• Issue signed JWT access tokens on successful login
• Protect at least one resource route with JWT middleware
• Implement token expiry and return 401 on invalid/expired tokens
• Store users in a database with unique email constraint

Build a service that shortens long URLs and tracks redirect analytics per short code.

• POST endpoint accepts a long URL and returns a unique short code
• GET endpoint redirects short code to original URL with 301/302
• Track click count and last-accessed timestamp per short code
• Reject invalid or malformed URLs with descriptive errors
• Persist all data to a database

Develop a full-featured blog backend with users, posts, comments, and role-based access control.

• CRUD for posts and comments tied to authenticated users
• Role-based access: admins can delete any content, users only their own
• Paginate post listings with configurable page size
• Support tagging posts and filtering by tag
• Write at least 10 integration tests covering key endpoints

Build a chat server supporting multiple rooms using WebSockets, with message persistence.

• WebSocket server handles connect, disconnect, and broadcast events
• Users join named rooms; messages are scoped to the room
• Persist last 50 messages per room in a database
• REST endpoint returns chat history for a given room
• Handle disconnections gracefully without crashing the server

Create a backend for an online store covering products, cart, orders, and basic inventory management.

• Product catalog endpoints with search and category filtering
• Cart service that calculates totals including discounts
• Order creation that atomically decrements inventory (database transactions)
• Order status workflow: pending → confirmed → shipped → delivered
• Emit an order-placed event to a message queue (e.g. Redis pub/sub or RabbitMQ)

Build an API gateway that proxies requests to downstream services and enforces per-client rate limiting.

• Proxy HTTP requests to at least two mock downstream services
• Enforce sliding-window rate limiting per API key using Redis
• Return 429 with Retry-After header when limit is exceeded
• Log every request (method, path, latency, status) to a structured log store
• Expose a /metrics endpoint with request counts and p95 latency

Design a distributed task queue where producers enqueue jobs and worker processes execute them with retry logic.

• Producer API enqueues jobs (e.g. send email, resize image) with priority levels
• Worker pool picks up and processes jobs concurrently
• Failed jobs retry up to N times with exponential back-off
• Dead-letter queue stores jobs that exceed retry limit
• Dashboard endpoint returns queue depth, active workers, and failed job count

Architect a backend where isolated tenants share infrastructure but have fully segregated data and configuration.

• Tenant provisioning endpoint creates isolated schema or database per tenant
• All API routes resolve tenant context from subdomain or JWT claim
• Per-tenant feature flags control access to premium endpoints
• Rate limits and quotas enforced independently per tenant
• Audit log records every mutating action with tenant ID, user ID, and timestamp