Interviewers in 2026 still ask Java collections and SQL joins. Full-stack loops add: how you designed an API, stored auth, tested a flow, and deployed it. If you added an LLM/RAG feature, expect “what happens when the model is wrong?”
Backend
- How do you version and validate a REST API?
- Entity vs DTO vs projection — why not return entities?
- Where do you put transactions? What breaks without them?
- JWT vs session cookies for your app — trade-offs?
Data and performance
- N+1 queries with JPA — how did you find and fix them?
- Index you would add for a common listing endpoint.
UI and integration
- How does the frontend store tokens and recover from 401s?
- What did you test: unit, API, or UI?
Engineering
- Walk through a PR you are proud of.
- How would you add an AI support chat without leaking other customers’ data?
Build the projects first; then these questions become stories. Flagship program