Backend Developer 路 Intern to senior
Backend interviews test how you store, process and serve data reliably: language fundamentals, SQL and indexing, concurrency, API design and how systems behave under load.
131 questions
Accept notification requests through an API, put them on a message queue, and let channel-specific workers (email, SMS, push, in-app) send them using user preferences, templates, retries with idempotency and rate limits.
Clients keep a persistent WebSocket connection to stateless chat servers; messages are stored durably, routed to the recipient鈥檚 server through a pub/sub layer, and delivered as push notifications when the recipient is offline.
Store file contents as chunks in object storage and file metadata in a database; clients upload chunks directly with pre-signed URLs, a sync service tracks versions and changes, and a CDN serves downloads.
Show how you built trust, understood competing concerns, used evidence and helped the group reach a decision.
Explain the constraints, alternatives, trade-offs, decision criteria and why the chosen option was appropriate for the context.
Cover detection, communication, mitigation, investigation, recovery and the changes made afterwards to reduce recurrence.
Explain why the technology looked attractive, what problem it actually solved, and why its cost or complexity was not justified in your context.
Explain the deadline, the quality risks, what you protected, what you simplified and how you managed any remaining debt.
Explain the original reasoning, the evidence that changed your view, how you corrected course and what decision-making practice improved afterwards.
Walk through how you shaped the problem, planned the work, aligned stakeholders, managed risks and measured the outcome.
Show empathy, clear expectations, practical support and appropriate escalation rather than blame.