API Projects That Prove You Can Build Backends

Most API tutorials build the same to-do CRUD. These are real backend API problems you solve in a live workspace - a wrong status code that breaks clients, a JWT check that accepts any token, a missing rate limiter, cursor pagination, a webhook signature to verify - and each one becomes a portfolio piece.

Why real API problems beat another CRUD clone

A CRUD clone shows you can wire a framework; handling auth, error contracts, rate limits, and idempotency shows you can build an API a team would actually run. These drill the parts interviews probe and clones skip.

24 projects to start with

Stream a RAG Answer With Inline CitationsAI/ML · SeniorRefactor Globals Into Dependency InjectionBackend · SeniorDesign a URL Shortener (System Design)Backend · SeniorMake a Stripe Webhook Idempotent (Retry-Safe)Backend · SeniorTrace Slow Requests With OpenTelemetryBackend · SeniorReplace LIKE Search With Postgres Full-Text SearchFullstack · SeniorMove JWT to httpOnly Cookies (XSS + CSRF)Security · SeniorBuild an LLM Content Moderation ServiceAI/ML · MidMake an LLM Pick the Right Tool (Function Calling)AI/ML · MidStop a Double-Charge Race ConditionBackend · MidInstrument an API With OpenTelemetryBackend · MidStream Tokens Over Server-Sent Events (SSE)Backend · MidVerify a Stripe Webhook Signature (HMAC)Backend · MidCache a Slow Endpoint With AWS ElastiCacheBackend · MidPlug a Postgres Connection Pool LeakDevOps · MidIndex a Slow Postgres Search QueryDevOps · MidConfigure an Nginx Rate LimitDevOps · MidMake an App Wait for Postgres on StartupDevOps · MidAdd a JWT Login and a Protected Route in ReactFullstack · MidFix the AI Chat That Dumps the Whole Reply at OnceFullstack · MidImplement Cursor Pagination for a 'Load More' FeedFullstack · MidImplement OAuth 2.0 With PKCESecurity · MidFix an IDOR Exposing Other Users' InvoicesSecurity · MidBlock an SSRF in a URL FetcherSecurity · Mid

Pick by the skill to show

Contracts and correctness? The status-code and validation ones. Security? The JWT and webhook-signature ones. Scale? The rate-limiter and pagination ones. Each finished fix is evidence on your portfolio.

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