Updated September 2026
Interview a startup full-stack engineer in four stages: a short screen, a walkthrough of a feature they built end to end, a pairing or take-home task that touches both the interface and the data, and a product conversation with the founder or product lead. Test their stronger side in depth and their weaker side for competence, because you will depend on both.
The full-stack interview plan
Building across the stack
- Walk me through a feature you built alone, from the first screen to the database. What would you change now?
- How do you decide where logic lives: in the browser, the API or the database?
- Tell me about a performance problem a user noticed. Where was the cause?
- How do you handle a form that saves data across several steps?
- What does your ideal API response look like for a list page with filters?
- Which part of the stack do you least enjoy, and how do you stay competent in it?
Strong answer: traces a feature through every layer with real detail and gives a clear reason for where logic sits.
Red flags: goes vague the moment the conversation reaches their weaker side, or blames "the backend team" or "the frontend team".
Product sense and users
- Tell me about a feature you talked a founder or product manager out of, or into.
- What did you learn from the last customer call you joined?
- Here is a request we received last week. What would you ask before building it?
- How do you know a feature you shipped worked?
- When have you shipped something you weren't proud of? Why was that the right call?
Strong answer: questions about the user's problem, a smaller first version, and a way to check usage after release.
Red flags: builds exactly what the ticket says every time, or has never looked at how a feature was used.
"How should it look? Can I get the designs and the acceptance criteria?"
"Who asked, and what were they trying to do when they hit the gap? Could we solve most of it by changing the existing page instead of adding a new one?"
Quality and speed
- What do you test on the frontend, and what do you skip?
- Tell me about a regression you shipped. How did it get through?
- How do you keep a growing React (or equivalent) codebase from becoming hard to change?
- What do you check before you ask for a review?
- How do you handle empty, loading and error states?
Strong answer: tests matched to risk, a calm account of a mistake and what changed, and attention to states most people forget.
Red flags: no tests at all, or a rule of testing everything regardless of cost.
Startup fit
- What is the fastest you have taken something from idea to customers?
- How do you feel about working without a designer?
- What would you want to build first here, from what you've seen of the product?
- What kind of work would you not want to do in this role?
Strong answer: pace with care, comfort making UI decisions, and specific ideas about your product.
Red flags: expects detailed specs and designs for every task, or hasn't looked at your product.
Work sample: add a feature to a small app
Give candidates a small repo with a list page backed by an API and a database. Ask them to add saved filters: a user sets filters, names them, and can reload them later. Cap it at three hours and ask for a few lines on what they would do with another day.
Look for a working feature end to end before any polish, a sensible data model, the empty and error states handled, and tests on the saving logic. In the debrief, change a requirement ("filters should be shareable with teammates") and watch how they adapt the design.
Scoring rubric
| Outcome | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| End-to-end delivery | Task incomplete on one side | Works, but one layer is weak | Complete, sensible across layers | Complete, clean, and well explained |
| UI quality | States missing, hard to use | Happy path only | All states handled, clear UI | Thoughtful details a user would notice |
| Backend soundness | No real data model | Works, awkward to extend | Clean model and API | Handles the changed requirement easily |
| Product judgement | Builds the literal request | Asks a few questions | Proposes a smaller, better version | Reframes the problem usefully |
| Speed with care | No tests, fragile | Tests in the wrong places | Tests on risky paths | Clear notes on what was skipped and why |
Where Funded.club fits
A dedicated Funded.club recruiter screens full-stack candidates on both sides of the stack before you meet them, with first screened candidates within 7 days on a fixed fee agreed upfront (see pricing).
Frequently asked questions
How many interviews should a full-stack engineer have?
Four stages over one to two weeks is usually enough, including a build task of three hours or less. Longer processes tend to lose candidates who have other offers.
Should I use a live coding test or a take-home?
Either works if the task looks like your real work and touches both frontend and backend. Offer the choice, since some strong engineers perform poorly while being watched.
What should I have ready before interviewing?
A clear JD and scorecard, such as our full-stack engineer job description template, and a plan for the search. Our guide on how to hire a full-stack engineer covers the rest.
Worth a brief chat about your next hire? Book a free call.
Hiring after a funding round?
First candidates in 7 days. Fixed-fee, no commission.