Hiring practice · 8 min read
How to vet a senior engineer: what we look for and why
How to assess senior software engineers: system design, hands-on coding, reference checks and working style, plus common interviewing mistakes to avoid.
By Bakaya Partners ·
Hiring a senior engineer is a high-stakes decision, and the usual interview loop doesn't predict success particularly well. Whiteboard puzzles reward people who practise puzzles. Long take-home projects filter out busy people with options. Here is the approach we use when assessing engineers, and the thinking behind each part.
1. Start with a system design conversation
Senior engineers are paid for their judgement, so test judgement. Give them a realistic problem with constraints: a service that needs to handle growing traffic, a data model that must change without downtime, a team of four with six months. Then listen to how they reason.
Good signs include:
- They ask clarifying questions before proposing anything
- They name trade-offs out loud rather than presenting one answer as obviously right
- They consider operations: how it's deployed, monitored and debugged
- They adjust gracefully when you change a constraint
2. Look at real code, written in a realistic way
A coding exercise should resemble the job. A short, practical task that reflects the stack they'll work in shows far more than an algorithm puzzle. Pay attention to structure, naming, tests and how they handle errors. A senior engineer's code tends to be calm, readable and unsurprising.
Keep the exercise reasonable in length. If you wouldn't want to do it yourself on a Tuesday evening, assume strong candidates won't either.
3. Check references with specific questions
References are often treated as a formality, which is a missed opportunity. Ask questions that invite concrete answers:
- What was the hardest technical problem they solved while working with you?
- How did they handle disagreement about a technical decision?
- Would you work with them again, and in what role?
- What kind of support or environment helped them do their best work?
Listen for specifics. Vague praise tells you little. A story about a migration, an outage or a tough review tells you a lot.
4. Talk about how they work with other people
Many failed senior hires are technically strong and still don't work out, because of communication, ownership or fit with the team's habits. Spend time on how they give and receive feedback, how they handle ambiguity and how they raise problems early.
Interviewing habits that get in the way
- Asking trivia that a quick search would answer
- Letting one interviewer's taste decide, instead of agreeing on criteria beforehand
- Moving so slowly that strong candidates accept other offers
- Skipping the conversation about the actual job, its problems and its constraints
Why we do this before you meet anyone
We accept roughly the top 5% of engineers who apply, and each one goes through system design, coding and reference checks before we introduce them. That means your interview time can go toward what only you can judge: whether this person fits your team, your product and your pace. You can see how this fits into the wider process on our how it works page.
If you're building your own process, we hope this helps. If you'd rather meet engineers who've already been through one, tell us what you need.