Declan Cummings
Head of Engineering

How Cinder Interviews Engineers

Declan Cummings
Head of Engineering

Engineers are at the center of everything we do at Cinder, so hiring people with the right skills to succeed at our stage of development is critical. Our engineering interview process is designed to identify those individuals. We designed the loop with the candidate’s experience and our company’s growth in mind. The interview sets us apart from other companies, yet also provides actionable signal about a candidate’s potential for impact at Cinder.

Interview goals: candidate measurement and company introduction

Starting out, the founding team knew that we needed engineers to contribute from day one. Joining a small and fast-moving team, new hires should have minimal ramp up time and be adept at unblocking themselves.

At the same time, we were operating in stealth mode: we had no public presence and little to no name recognition. Interviews were our chance to sell our vision to candidates in a job market that was, and remains, extremely competitive.

The options available didn’t cut it

We weren't impressed by more traditional engineering interviews:

  • LeetCode-style: These interviews emphasize theory and have a tenuous correlation with engineer productivity. They also don’t introduce the candidate to the company’s product, challenges, and engineering culture.
  • Take-Home: Take-home projects test how candidates perform on challenges that mirror those faced every day by the company. This style scores high for relevancy, but take-home interviews require a lot of time from candidates. We couldn’t expect candidates, many of whom had demanding day jobs, to sink hours into a take-home assignment for our new and relatively unknown startup.
  • Paid, in-person trial: We knew some companies pay candidates to work alongside the team for a period of time. Though this style also scores very highly on relevancy, it runs the risk of losing candidates who can’t take time off their day jobs. It also requires a lot of time investment from the interview team and carries security and privacy risks.

The solution: a loop that achieves our goals and minimizes cost

Our engineering interview is three hours in total. Candidates start with a Cinder engineer over Zoom for introductions and an overview of the challenge. Candidates are then granted access to our interview repository and given a total of two hours to complete a full-stack challenge that closely mirrors the type of problems we encounter every day at Cinder. The challenge is broken down into steps that become progressively more difficult and open-ended. The steps build on each other, allowing candidates to scaffold their knowledge and demonstrate both breadth and depth across our stack. After the coding portion, we reconvene over Zoom with the candidate to review their work, discuss how they overcame uncertainty, and consider how the solution might scale in production. This is also a great chance to pair to work through any remaining questions and test how candidates handle feedback on their code.

We are clear with candidates that we don’t expect them to come into Cinder with fluency in all aspects of our stack. Instead, we want to see how they unblock themselves when they inevitably encounter something they haven’t seen before.

We always tell candidates the interview is a two-way street: we want to measure their ability, but we also want them to consider whether this type of challenge, and this stack in particular, is something they’d enjoy working on full-time.

The interview is both predictive and enjoyable

So far, the interview has produced great results. We’ve hired a stellar team with an average ramp up of under a week. We trust that our engineers can work independently, yet we also know that they can describe their code effectively.

Candidates consistently give our interview great reviews. Many describe it as the best coding interview they’ve encountered. No matter the outcome, we want candidates to leave the interview with a positive impression of Cinder; this interview accomplishes that goal.

We’re hiring!

If this interview intrigues you, we encourage you to look at our open roles here: