What I Look For When Hiring a Senior Frontend Engineer

What I Look For When Hiring a Senior Frontend Engineer

After running interview loops for senior frontend roles, I’ve narrowed down the signals I actually trust. “Knows React well” isn’t one of them. That’s a baseline, not a senior signal.

This post is what I look for, what I ignore, and what’s saved me from bad hires.

1. They show their thinking, not just the answer

Mid-level candidates jump to a solution. Senior candidates start with “what’s the constraint we’re optimizing for?”. They ask about traffic patterns, team size, deploy frequency, who’ll maintain the code in six months.

If a candidate accepts the problem as given without checking the framing, they will do the same on your team. That’s expensive.

2. They’ve shipped something they later had to live with

Senior frontend isn’t about clean greenfield code. It’s about migrations, deprecations, and the bug you can’t reproduce that’s costing you a customer a week.

A question I keep coming back to: “What’s a piece of code you wrote two years ago that you’re still maintaining? What would you change?”. The answer tells me more than any take-home.

3. They have opinions about tradeoffs, not stacks

A senior engineer who only argues for their preferred stack is a junior in a senior’s clothes. The signal I want is tradeoff fluency. When does Server Components hurt instead of help? When is Tailwind worse than CSS modules? When does a monorepo create more pain than it removes?

If they can name the failure modes of their own preferences, they’re senior.

4. They’ve worked with non-frontend humans

The senior frontend role is half tech, half communication. Backend engineers who don’t trust the FE team. Product managers who keep changing scope. Designers who deliver mocks at the wrong fidelity. Juniors who need mentoring, not blocking.

I ask about the hardest cross-functional conflict they’ve shipped through. A vague answer is a flag.

5. They care about the boring stuff

Telemetry, build times, dependency hygiene, accessibility, error tracking. Senior engineers spot the missing pieces in your codebase, not just the new things they want to add.

A useful question: “What would you want to add to our dev workflow in your first month?”. If everything they say is glamorous (refactor X, adopt Y), they haven’t operated at scale. If half their list is “set up an error budget” or “add a bundle-size CI check”, they have.

Anti-signals

A few things that don’t predict seniority on their own:

• Years of experience. I’ve met four-year engineers who were more senior than twelve-year ones.
• Big-company logos. Prestige doesn’t translate to ownership.
• Open-source profile. Useful evidence, but plenty of strong seniors don’t have one.
• Clean LeetCode performance. Wrong problem for frontend.

Conclusion

Senior frontend is about judgment under constraint. Hire for the candidate who frames the problem before solving it, who’s lived with their old code, and who notices the unglamorous gaps.

Summary

The five signals I trust: showing thinking before answering, having lived with their own code, fluency in tradeoffs (not stacks), cross-functional conflict experience, and caring about boring infrastructure. The signals I ignore: years of experience alone, big-company logos, LeetCode performance.

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If you’re hiring and the senior pipeline is months out, I take on contract and fractional engagements for exactly this gap. See hire a frontend developer.