Interview practice by role
Backend Developer Interview Practice
Backend interviews focus on data, APIs and failure. You are expected to reason about indexes, consistency, caching and what happens when a dependency is slow or down.
200 practice questions5 topics5 typical rounds
How the interview usually runs
Loops differ by company. Treat this as a common pattern, not a fixed format.
- 01Screening callYour stack, the scale you have worked at and one or two language or HTTP basics.
- 02Language and runtime deep diveConcurrency model, memory, error handling and the details of your main language.
- 03Data and API designSchema design, indexes, query plans, API contracts, pagination, versioning and idempotency.
- 04System designDesign a service with caching, queues and failure handling, and justify each trade-off.
- 05Behavioural roundIncidents you handled, on-call experience and how you review other people's code.
What interviewers probe
- Data modelling and how an index changes a query
- API contracts: idempotency, pagination, errors and versioning
- Caching strategy and how you invalidate it
- Consistency versus availability when something fails
- Observability: logs, metrics and how you debug production
Common mistakes
- Designing for scale before stating the actual load and requirements
- Naming a technology without saying what problem it solves here
- Forgetting failure cases such as retries, timeouts and duplicate requests
Practice questions for Backend Developer interviews
A starting set from each topic. Every question has a short answer, the full reasoning and the follow-ups interviewers ask.
01How does the Node.js event loop work?Mediumevent loop · libuv · async02Is Node.js single-threaded? What does that actually mean?Mediumnodejs · concurrency · libuv03How do you handle errors in a Node.js backend?Mediumerror handling · async · reliability04How do you choose between SQL and NoSQL databases?Mediumsql · nosql · data modelling05What is the difference between WHERE and HAVING?Mediumwhere · having · aggregation06What is the difference between INNER JOIN and LEFT JOIN?Mediuminner join · left join · nulls07What does the CAP theorem actually say?Mediumcap theorem · consistency · partition tolerance08How does eventual consistency work and how do you handle it?Mediumeventual consistency · replication · session guarantees09How do wide-column stores organise data?Mediumwide-column · cassandra · partitioning10How does load balancing work and how do you choose an algorithm?Mediumload balancing · l4 · l711How does database sharding work and what are the pitfalls?Mediumsharding · partitioning · hotspots12How does database replication work and what consistency issues does it create?Mediumreplication · replication lag · failover13Why are you leaving your current job?Mediummotivation · professionalism · job change14What is your greatest weakness?Mediumself-awareness · growth · weakness15What is your proudest achievement?Mediumimpact · storytelling · ownership
Reading is step one
Now say it out loud.
Understanding an answer and delivering it under pressure are different skills. Rehearse this topic in a live Backend Developer mock interview and get scored feedback on depth, clarity and confidence.