Demystifying product interviews

TransferWise engineering interview process consists of several steps which can be broadly outlined as following:

  • Screening
  • One or two technical interviews
  • Product interview
  • VP engineering and Founder interview

The third step in the process - product interview is somewhat unorthodox and may leave some candidates puzzled and struggling. To make this transparent we are sharing a post to explain why we do product interviews and how to be successful in a product interview.

Why we do product interviews

Engineers across disciplines make a world of difference. Civil engineers strive to design large scale structures – Channel Tunnel was built to transport 20 million passengers between England and France every year. Mechanical engineers design efficient power stations in order to generate electrical energy for nations. Aerospace engineers design aircraft to transport people and goods from between continent efficiently at near supersonic speeds. Electrical engineers design integrated circuit boards for LCD televisions for people to enjoy high definition and 4K content.

Engineers in TransferWise design and build software to move money between countries efficiently, rapidly and conveniently for our users.

Our work in TransferWise engineering is incredibly complex and multi-disciplinary, touching on computer science, data science, software engineering, compliance and AML, banking, foreign exchange, payment systems, distributed systems infrastructure, user behavior, efficient use of resources and much more. It would be easy to get super focused on some small aspect of this large universe and spend way too much time and resources on perfecting something that’s good enough already. By staying focused on the problems our users have, we clarify our own thinking about the right path forward.

The Turing award nominee of '99, Frederick Brooks mentions in his infamous paper titled “No silver bullet” that:

“The hardest single part of building a software system is deciding precisely what to build.”

Product interview is designed to evaluate a candidate's ability to decide precisely what to build and succeed in independent and autonomous teams. It is about really understanding every detail about the problem being solved and evaluating the success of the solution through build-measure-learn cycle practiced to perfection across engineering disciplines. Product thinking in engineers and product interview process are a key to scaling our organization and building a service for sending money abroad 10 times better than current prevailing methods.

What happens in a product interview

By the time of the product interview it is already clear that the candidate has impressed with his technical fundamentals, programming skills and has the ability to solve problems on the fly. Questions one can encounter during product interviews are less technical and involve product thinking, product development methodologies, data-driven decision making and also case studies. Some examples for type of questions that can come up during product interview are below.

Product thinking:

  • Have you used the TransferWise product? How would you improve it?
  • What have you started/built on your own? Why?
  • Have you spoken to a customer? Why? What did you learn?
  • What will you do if nobody tells you what to do? Or when everyone else is on vacation for 2 weeks? For 2 months?
  • What is a great product you have encountered recently. Why do you like it?
  • What's made [insert product here] successful?
  • What problems are we going to encounter in a year? Two years? Five years?
  • How do you know a product is well designed?
  • What was your biggest product mistake? (many developers often say that they’ve never made a product mistake)
  • Do you like to take initiative (when was last time?); or do you prefer to have detailed spec?
  • What’s the coolest thing you’ve built / product that you are most proud of?

Product development methodologies:

  • Lean engineering principles
  • Outline 5-7 steps from idea to realized product (from establishing hypothesis to testing it against measurements)
  • Describe build-measure-learn / typical startup execution cycle
  • What is an MVP?

Data-driven decision making:

  • How would you measure the success of X?
  • What would you choose as top 5 metrics for TransferWise as a company?

Case studies:

  • How would you design a fraud system monitoring suspicious transactions?
  • How would you design a delivery estimator predicting when the money arrives to a recipient in a foreign country?

So what should one do as a candidate facing one of these product interviews?

  • Come in prepared. It really helps to familiarize yourself with the business of the company
  • Make sure you fully understand the question and problem on hand
  • Be creative and think about the big picture and wider impact of the change
  • Use examples and draw parallels of what you have done and has worked well previously
  • Ask questions. Asking interesting questions is a good way to share what you are interested in and is also yet another opportunity to stand out

We hope you enjoy the process!