The standard software engineering interview was designed to filter hundreds of candidates for a large company with predictable, well-scoped work. It was not designed for a three-person startup with an ambiguous problem and a codebase that changes direction every two weeks.
Yet most founders who hire their first engineer use some version of the same process: a recruiter screen, a technical phone call, a take-home problem or live coding session, and a culture-fit conversation. The outcome is usually disappointing. Not because the engineer is bad, but because none of those signals predicted what actually mattered: can this person figure out an unclear problem, ship something real, and communicate clearly while doing it?
I have hired first and second engineers at three startups and conducted engineering hiring for more than a dozen early-stage companies as a fractional CTO. I have made a significant number of mistakes doing it. This is what I learned.
Why Standard Interviews Fail Here
At a mature company, the job is well-specified. A senior engineer on a FAANG team knows what a ticket looks like, what the review process is, and what the production standards are. Behavioral questions predict fit because the context is stable.
At a seed-stage startup, the job description includes "and everything else we have not thought of yet." The work is ambiguous. The codebase is often inconsistent. The product direction shifts. The person who thrives in that environment has a specific set of traits: comfort with ambiguity, strong communication under uncertainty, the ability to make a reasonable decision with incomplete information and move forward.
LeetCode problems test whether someone can solve a constrained algorithmic puzzle under time pressure. That skill has approximately zero correlation with the ability to read a messy codebase, identify the most important problem to fix, and ship something useful in a week.
The Boring Reality
A trial project is not a trick. It is the closest approximation of actual work that you can create within the constraints of a hiring process.
The format I use has four non-negotiable properties.
Paid. The candidate is compensated at a fair daily rate, typically $200 to $500 per day for a senior engineer. If you will not pay for a trial, you are extracting free labor. Do not do that.
Real. The project comes from your actual backlog. Not a toy problem, not a sanitized fake codebase. A real task that needs to get done.
Time-boxed. Three to five working days. Long enough to see how they handle ambiguity; short enough that strong candidates can make time for it while employed.
Async-first. They work from wherever they work, communicate in writing, and use your actual tools (Slack, Linear, GitHub). This tests real working style, not interview performance under observation.
Designing the Right Project
The project design is where most teams get it wrong. They pick something too narrow ("fix this specific bug") or too broad ("build a feature from scratch"). The goal is a task that requires judgment at multiple levels.
The best trial projects have these properties.
Genuine scope ambiguity. The requirements are written the way real requirements get written: with gaps. The candidate has to ask clarifying questions or make documented decisions. How they handle those gaps tells you more than their code.
A known landmine or two. There is something in the codebase or the problem that a thoughtful person would notice and flag. Maybe a performance issue, a security concern, or a design decision that will cause pain later. You are not testing whether they catch it; you are testing whether they mention it.
Multiple valid solutions. There is no single right answer. You want to see how they reason about tradeoffs, not whether they arrived at your pre-specified solution.
An explanation requirement. At the end, they write a short document (one to two pages) explaining what they built, why they made the choices they did, and what they would do differently with more time.
The Scoring Framework
Do not evaluate the trial project subjectively. Use a rubric.
| Dimension | What You Are Evaluating | Weight |
|---|---|---|
| Working code | Does it actually work as described? | 20% |
| Problem framing | Did they ask the right questions and flag real concerns? | 25% |
| Communication | Clear async updates, readable written explanation | 25% |
| Judgment on tradeoffs | Did they make reasonable decisions where scope was ambiguous? | 20% |
| Scope management | Did they manage their time appropriately across the trial days? | 10% |
The communication score is the most predictive of long-term fit at an early-stage startup. Engineers who produce clear explanations of their decisions integrate faster, create less ambiguity, and are significantly easier to work with as the team grows.
The Interview Structure Around the Trial
Do not skip conversations entirely. The trial works best inside this structure:
30-minute intro call. Cover the role, the problem you are solving, and the trial format. Get a read on communication style before you commit to paying for the trial.
Trial project (three to five days, paid).
90-minute debrief. Walk through their explanation document together. Ask them to defend their choices, especially the ones you disagreed with. This is where you distinguish good communicators from good writers.
Reference checks (two calls, not emails). Ask the references: "Tell me about a time this person had to figure out something that was not well-defined." The answer is more predictive than any formal interview question.
What I Got Wrong
My earliest trial projects were too well-specified. I wrote detailed requirements because I was afraid of wasting the candidate's time or creating confusion. The result was that the project tested execution (can you follow clear instructions?) rather than the actual skill I needed (can you figure out what to do when instructions are incomplete?).
The second mistake was not paying. At two early startups I used unpaid trials, rationalizing that the candidate would benefit from the experience. I lost three excellent candidates who declined after learning it was unpaid, and I deserved to lose them. Beyond fairness, paid trials also signal that you run your company with integrity, which is a useful first impression for someone deciding whether to join you.
The third mistake was hiring someone because their code was beautiful. They were a slow communicator, resistant to pivoting, and had strong opinions about how problems should be framed before they could be solved. Excellent code quality does not compensate for poor fit in a three-person environment.
Red Flags During the Trial
These patterns reliably predict a bad hire.
Zero async communication during the project. Someone who disappears for four days and submits a pull request at the deadline has told you exactly how they will operate when things get hard.
Ignored ambiguity. They plowed forward without acknowledging the gaps in the requirements. Either they did not notice (a judgment problem) or they noticed and did not raise it (a communication problem). Both are bad signals at this stage.
Overengineered solution. They built a framework when you needed a feature. At an early startup, this pattern compounds quickly and becomes expensive to unwind.
Defensive explanation. "I did X because X is the right way to do it" versus "I did X because of Y and Z, and I am uncertain about W, which I would revisit with more time." The second candidate understands tradeoffs. The first may become a liability when you need to change direction.
The One Question That Replaces Most Behavioral Interviews
After the debrief, ask one question: "Walk me through the last time you had to ship something under significant uncertainty about what the right solution was. What did you do?"
Strong candidates describe a process: how they gathered information, what decisions they made without enough information, how they communicated uncertainty to stakeholders, what they learned afterward. Weak candidates describe a solution. The solution is not the signal; the process is.
When NOT to Use This Format
Trial projects work poorly in two scenarios. First, if the candidate is currently employed and cannot carve out five days, a one-day compressed version can work but loses signal on the ambiguity-handling dimension.
Second, for very senior hires (CTO, VP Engineering) where a trial project can feel inappropriate given their track record. For those roles, a structured portfolio review plus two hours working through a real architectural decision together substitutes well.
For the first three to five engineering hires at a seed-stage startup, the paid trial project is the most reliable signal I have found. It costs a few hundred dollars and a week of coordination. A bad first engineering hire at a startup costs an order of magnitude more in both money and time.