Structured Tech Interview

Each assessment is structured in three parts:

Intro

We begin with a brief intro on both sides as an ice-breaker. The Interviewer then walks the candidate through the agenda and what to expect.

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Questions

We spend 30 minutes going through technical questions carefully designed to evaluate the technical knowledge of the candidate based on their position and level.

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Challenge

The interview concludes with a practical coding task which the candidate is invited to complete. The interviewer provides support to help the candidate succeed.

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An illustration of an interviewer and a candidate doing a coding challenge.

1. The Introduction

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Every interview begins with a brief introduction from both sides.

The interviewer helps the candidate relax during this ice-breaker part, and to establish an atmosphere between colleagues. As such clarifying questions or asking for help during the assessment feels natural - as if two colleagues are sitting next to each other, discussing how to solve a challenge at work.

This introductory part doesn’t only set a relaxed tone but it also gives an opportunity for the candidate to communicate other strengths, such as traction or experience at his current or previous jobs.

The interviewer also sets the agenda for the meeting while providing the candidate with useful pointers.


2. The Questions

Each interview is tailored towards the candidate and the position in question. To ensure a fair base level for evaluation, all the questions and coding tasks are standardized for a position and do not undergo changes once the first candidate has been interviewed.

We begin by asking the candidates flash questions. These questions assess basic knowledge when it comes to a framework or tech stack. An example includes listing the ruby runtime frameworks or asking about very specific culprits related to a tech stack on nodes.

An illustration of an interviewer and a candidate asking a lot of questions.

Flash question: Name the Ruby application servers you know and the biggest differences between them.

An experienced ruby guru would list MRI, JRuby, mruby as runtimes and list at least unicorn, puma, passenger as servers and explain the difference on how threads and processes are handled as well as outline specific culprits, such as a zero-downtime deployment possibilities.

A flash question like this tests if the developer has a deeper understanding of the inner workings of ruby and if the candidate has experience with the challenges of scaling Rails applications. Once we have established the baseline we continue with in-depth hard skill questions which are always tailored towards the position.

Here are some characteristics of great questions:

Testing the hard skills in-depth

During this standardised assessment we track the candidate’s performance in various dimensions - we assess if the candidate has prior experience in that field, we evaluate the thinking process and the overall approach to solutions. Apart from the pure hard tech skills which test concrete technical stack and frameworks, we also make notes how the candidate approaches challenges in a team environment and if they go beyond the technical requirements within an organisation.

Standartised Questions and Grading


In order to create a fair baseline, we prepare 10-12 questions tailored to each position. This way, every candidate is evaluated fairly among their peers. We use a standardised grading scheme: Fail, OK, Great, Exceptional points for each question. Most candidates fall between OK and Great, and the Exceptional score is given only to very experienced developers who go way and beyond the standard understanding and have the knowledge, experience and can provide several solutions within different scopes.

Holistic, yet concrete questions

Generally, when interviewing developers we always split the questions into several categories depending on the tech stack and the position. As such there are questions targeting the specific language and framework, databases, devops knowledge and specific skills applicable only to that position and level.
Let’s say we are assessing a Senior Ruby developer. In such case we would ask questions specific to the ruby runtimes, the Rails framework, specific culprits and CI strategies specific to the ruby backend but also test how the developer makes architectural decisions.

Which are the right questions?

We can help you tailor the questions for each technical interview based on the position and requirements.

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Holistic question: In a standard Rails app with users, how do you ensure that a user and their data are permanently deleted? Think of the whole organization.

Why do we ask that question?

We love asking questions like this because they don’t only test the hard skills and experience but also provide a real life use-case and challenge that many developers already had to face. It goes above and beyond simple technical solutions and makes exceptional candidates with experience stand out. Does the candidate simply think of database associations? What about backups and external services? Has the candidate ever dealt with GDPR and what was their past experience and attitude towards data privacy?

Here's how we grade that question:

OK: The candidate takes into account that an ActiveRecord model with a table of users has associations and dependencies and those need to be destroyed as well. The candidate shows basic knowledge when dealing with association dependencies, the ActiveRecord ORM and knows how to handle dependencies, delete avatars, execute after triggers, etc.

Great: The candidate doesn’t only take into account that the user and the data have to be deleted but also ensures that backups have an expiration date and uses background jobs and a queue to delete user data from third party services. Documentation and tests are added to ensure that future modifications or additions are also handled and tested.
Exceptional: The candidate doesn’t only fulfill the technical requirements but they also consult their organisation’s legal department regarding GDPR and training. The candidate also approaches the product team to ensure that the Right To Be Forgotten is executed, the user is informed, the data expiration dates are set and ensures there is a company-wide policy when it comes to using data processing services. When it comes to billing data which needs to be retained the accounting department is involved, when it comes to calculating KPIs such as user acquisition and retention anonymisation of the stats is performed so that the data is not skewed.
An illustration with the words OK! Great! and Exceptional! as a grading scheme.

You do not always need a developer with exceptional knowledge or skills

If you are hiring a CTO, Tech Lead or a Software Architect you most definitely need a candidate with an exceptional organisational and structural knowledge as well as the experience to think about the big picture first. However, If you are hiring a mid-level backend developer and want to integrate them in your tech team then the requirements would be very different and the grading scheme and assessment would be adjusted.

It takes a CTO to hire a CTO

If you are hiring your next CTO or tech lead you should ensure that their skills are on par. An external CTO can effectively identify and assess the right candidate for the job.

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3. The Challenge

The last part of the assessment involves assessing the candidate’s hands-on skills in a screen sharing session. A coding challenge is given which lasts about 30 mins and the candidate must solve it without using any AI tools.

During this part, sometimes also falsely called Pair Programming, the candidate may ask questions and may google resources but is not allowed to search for specific solutions. While the solution of the challenge bears the highest weight for the evaluation, we also make notes about several other factors:

Big O

• What is the complexity of this solution?

• How did the candidate approach the problem?

Code Quality

• Did the candidate test the solution?

• What IDE was used?

Logical Thinking

• What corner cases were discussed?

• What sort of help did the candidate need?

An illustration of an interview setting during the coding challenge part with a screen in the back saying 'success!'.
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A Full Tech Interview Report

After each interview we compile a detailed PDF report with our assessment of the candidate that can be attached to their resume and used for the current and other future positions they may apply to. Here is what you can find inside:

  • Where did the candidate do great and what are their biggest strengths based on their knowledge and experience
  • What are the candidate's concrete skills that lack or need improvement for the position
  • Detailed assessment on each technical question with grades
  • General gut feeling by the interviewer which also includes possible red flags, evaluation of prior experience and culture fit
  • Recommendations on how to help the candidate get better
  • Personalised candidate feedback (ready to be sent)
  • Overall Candidate Score & Hire / Don't hire recommendation

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