How to Interview Frontend Engineers

Interview for the craft, not the framework

Most frontend interviews test the wrong thing. They either bolt on an algorithm puzzle that has nothing to do with the job, or they check whether the candidate has memorised one framework’s API. Both miss what actually makes a frontend engineer effective: mastery of the fundamentals underneath, and the judgement to build the right interface well.

Front-end work is practical, so the interview should be practical too. The strongest signal comes from realistic tasks that look like the job, scored against what good actually means for your team.

Test the fundamentals beneath the framework

Frameworks change; the fundamentals do not. Screen for genuine depth in:

• HTML and accessibility — semantic markup, keyboard support, ARIA where it earns its place.
• CSS and layout — the box model, flexbox and grid, responsive behaviour, and why something reflows.
• JavaScript and the browser — the event loop, async, the DOM, and what actually costs performance.
• State, rendering and performance — managing state without tangling it, and keeping the interface fast.

A candidate fluent in React but shaky on the browser underneath will struggle the moment the tooling changes. One who understands the platform adapts to any framework.

Use a realistic build, not a puzzle

Replace the abstract screen with something close to the work: build a small component with state (a typeahead, a data table, an accessible modal), or review a non-trivial pull request and talk through what you would change. Let candidates use their normal editor and search the way they would at work. Work samples are among the highest-validity predictors precisely because they measure the thing you are hiring for. If the role uses a specific stack, run it there — our React developer hiring and TypeScript hiring pages cover what to look for.

Calibrate to seniority

Match the task to the level, or you will get false signals in both directions:

• Junior — core HTML, CSS and JavaScript, and clear reasoning about basics.
• Mid-level — build a common feature end to end with sensible state and edge cases handled.
• Senior — open-ended problems with real trade-offs, plus performance, accessibility, security and how they collaborate with design and backend.

What makes a senior stand out

At senior level, framework fluency is assumed. The differentiators are judgement and communication: reasoning about trade-offs, debugging methodically under ambiguity, treating performance and accessibility as defaults rather than afterthoughts, and explaining decisions so the rest of the team can follow. A senior who name-drops libraries but cannot justify a choice is a weaker hire than one who picks a boring, correct approach and explains why.

Keep it sharp, and close

A good process is also a quick one. The strongest frontend engineers are rarely on the market long, so keep the loop short, give feedback fast, and make sure every candidate hears from a real person.

Good frontend hiring comes down to seeing past the framework to the engineer underneath — which is exactly what our screen is built to do. If you are hiring, see how we hire frontend engineers and our React and TypeScript hiring guides, or talk to us and we will handle the screening.