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Programming translates concepts to reality — Laurent Cerveau (Zenly)

by Alban Dumouilla

Zenly is the social map app beloved by millions of teens around the globe. Free on iOS & Android, Zenly allows friends and families to share their live location to meet easily in real life. Acquired by Snap Inc in 2017.

What’s on your pizza?

We ended up in a ‘Bistrot’ instead of a pizzeria, oops. So no pizza this time but an ‘escalope milanaise’.

Let’s talk about you

What I love about programming is that before anything you need to think about what you want to do, and not how you’ll do it

What’s your background ?

I studied in France at ENSEA, and followed a PhD around audio and acoustics. During that time, I started coding a little bit — at around 28, which is late compared to a lot of CTOs nowadays. We had classes in Pascal and Basic — but I thought quite little of those. I generally prefer handling a guitar than a computer but I quickly realized that computing was a good way to actually make things happen.

I love to build things, to do any kind of manual work. What I like about programming is that before anything you need to think about what you want to do, and not how you’ll do it. Programming translates concepts to reality.

I then joined Apple for about 8 years, where I worked on a lot of projects — some that came out and others that didn’t. But the first few projects were around audio, which was really important to me.

The most fascinating thing at Apple is their very lightweight but very strong processes that allow having an extremely efficient delivery pipe. I learnt a lot of habits that I’ll probably keep for life, and each time I speak to my old Apple coworkers, it seems like they do as well.

I came back to France in 2001, and Apple opened their French R&D office around that time, which I joined to work on iCal and iSync. Apple bought a company that worked on audio software and I participated in the due diligence to make sure the buy was worth it and I moved to Hamburg, Germany for it in 2005.

After 8 years, it was time to move on. Joining a company, no matter how great, is a contract with yourself and knowing how long you are willing to jump in the train for. After that I launched a startup which didn’t work and a consulting firm.

How did you join Zenly?

Alexis and Antoine had a team member who knew what they needed, and thought that I could likely help doing it. The beginning of the adventure was a great intellectual journey, between us 3 and Nicolas, with a lot of thought process taking place towards what we wanted to do.

I am still very fond of the creative environment of those first few months, and somewhere I believe that a shape of it is still immaterially present in the company of today.

What does it mean, to be a CTO?

A CTO is here to make sure everything can happen on the technical side

A CTO is here to make sure everything can happen on the technical side. It’s a job that evolves constantly:

At first, you’re a developer, you just make things work.

Then you start building your team, and hiring takes a lot of your time. Hiring is far from easy and there’s no miracle way to do it right that I know of.

Once your team starts growing you become a manager. And that part of your job really depends on who you end up managing and who you are. The CTO is here to make his team grow, adapt to the team’s need and create the right environment for ideas to foster and the team to be productive.

The CTO needs to drive the team so that the most important things become clear to everybody. A few rules need to be followed, for example:

  • When you say you’ll do something, you have to hold to your commitment, and if there is a problem be honest about it.
  • You have the responsibility to make sure that what you build actually works and doesn’t just work in a test environment. For us, as a location based service, you need to go underground in a metro station to check how your app behaves when there’s actually no network

That means that the best tech guy in the team is not necessarily the CTO. Your role depends on the current spot the company is in and its needs.

The CTO needs to meet a lot of people. The more people you have good, genuine relationships with in other companies, the more help you’ll be able to get for free, just because people like you. It’s not a matter of owing anybody anything or doing favors — it’s a matter of helping because you can and because you like the person you’re about to help.

To come back to my role inside of Zenly, there are two main components to it:

  • Legal matters: European regulations are evolving and I’m monitoring the impacts that they will have on our company and taking action
  • Internal matters: When you join a bigger company like Snapchat, you need to handle the integration of your team in a very delicate way. How do you keep your team running in an optimal way with their new environment?

Let’s talk tech

What’s your tech stack?

We participated to a few conferences where we exposed in details how things run at Zenly, but I’ll go over it quickly: We run on Google Cloud Platform with an intense usage of Docker. We use ScyllaDB which is basically a faster C/C++ based implementation of Apache Cassandra. Our real time data pipeline is in Kafka, and we export it to HDFS for data-science purposes. We have code in Go and still have a few things running in Python.

The internal back office has a React front-end and uses ElasticSearch. For a while ElasticSearch was even our main storage engine!

For mobile, we use Go mobile for common parts and native languages on both platforms (Swift and Java)

Life as Zenly’s CTO

Most regrettable decisions are often about humans, not technology

Is there anything you’d have done differently now that you know where you are today?

Of course there must be a few things but in a global way, not really. I don’t think I’ve done any enormous mistakes, but some small mistakes can have big of an impact in the long term than ones that seem huge from the start.

A good example is when you need to let go of someone, you usually wait to see if things can get better. You wait because it would be accepting that you made a mistake by onboarding this person in the first place. And you often end up waiting for too long.

For me, most regrettable decisions are often about humans, be it in a positive or negative way, not technology.

Can you tell us about a crisis you had to manage in your life?

I won’t point a specific one as it wouldn’t be useful. We went through crises when going from a small group of people to a fast growing company, of course. For every person joining a team, they have to chose how long they want to follow a company’s track, and sometimes they leave. That’s always hard, but it’s OK.

A few of our early developers left the company over time. At the beginning, one developer can be 25% of your workforce! Every single one of these departures can be considered a crisis.

We always have to manage our external image: Since the acquisition, people tend to have a really different view of us compared to what’s really happening inside. We’re still normal people that eat and drink like the rest of the world, we still have to work hard.

People can be really attached to specific facts that don’t necessarily have an importance. I get asked if I shook Steve Job’s hand while working at Apple. I never answer this question — who cares? Would that change anything in our discussion if I did and if I never washed my hand since?

The only thing that matters is that the company moves in the right direction, no matter how.

About hiring

Is the story you’re telling me about really interesting or is it bullshit?

What are you looking for in somebody you’re looking to hire?

Can we have an interesting conversation? Can we think about working together in a high level way, can we actually enjoy building something together and be satisfied with it?

The main thing is personality, assuming skills and knowledge are here. Things can be a bit flat at the beginning during an interview, and then the candidate would light up while answering a specific question. Or the other way around, you can feel a good start that ends up being a false impression.

I often ask myself this question: Is the story that the person is telling me really interesting or is it bullshit?

Another thing I ask is what they think about Zenly. Anyone joining the company needs to have their own use of the application and needs to be able to tell me why it’s the best app for what they use it for, or how we can make it the best app for that.

Any tips for a startup looking to hire?

Spend time on it. Meet people, evaluate your interview process to know if you’re asking the right questions at the right pace or not. Are you looking for people that can execute well? People that can think in a certain way? Know what your needs are.

You should also check your competitor’s job postings. Find the tone they are using and find what tone you want to be using. Partner up with the right people, hiring firms or whatever you need.

When hiring a developer, there’s what I call the “dentist effect”. A bad developer looking for a new job will likely have good recommandations anyway, because people don’t want to admit that they are the last ones that got fooled by the guy in hiring them.

A bad hire costs a lot — financially and morally. So make sure you have everything in hand when you take a decision.

About success

I haven’t been bored in a long time

There are a few moments in life when you let go — you let yourself enjoy the moment to the fullest. Being acquired like we did takes some time to process.

When I was younger, my friends and I didn’t want boring lives. When I look back, I believe that for now I’ve done quite well in this regard. I haven’t been bored in a long time.

We live in a world where engineers and developers are kings. This creates a ‘star ecosystem’ where people want to be ninjas, rockstars, etc.

Rockstars are humans, like any of us. What really changed is how much other people’s opinion of us matters now. Everybody needs some recognition, but some are driven by it.

In tech like in music, the people that go the furthest enjoy the present and enjoy what they do. Most of them do well because they are passionate about what they do — look at Paul McCartney that is still kicking.

At Zenly, Antoine and Alexis (note: the founders) have this impressive drive. When you’re a C-level anywhere, your job is to ask yourself: “How can I make things move forward?”

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