Monzo Staff Weekly Q&A - Jonas Huckestein (Co-Founder & Chief Technical Officer)

Will you be doing any more Monzo hackathons?

Do you think new fintechs will ever displace the huge card network duopoly of visa and MasterCard? If so what path could they take?


Where are you going for your honeymoon :smiley:

Meri Williams will be officially taking over the role in September, while she handles her transition from Moo to Monzo. Huckestein, meanwhile, is off on his honeymoon.

Programming is something I’ve been interested in for a while, I did a module on it in Uni (Objective-C & C#) and I’d like to get more into it.

What languages are your favorites / do you use regularly and why?
What good resources are out there for beginners and what languages would you suggest I look into more?

Backend/app development interests me the most :slight_smile: :desktop_computer:

I created a thread about this if anyone wanted to post further: Programming


What one feature would you build & launch today if you had a magic wand?


:wave:Hey all, thanks so much for all the questions so far. I have set aside an hour this afternoon to answer them. Chat soon :soon:


Where do you see Monzo in December 2018?
How about in 5 years?
What do you think can stop Monzo from achieving its goal?

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What piece of advice (financial or otherwise) would you give to a young person/younger self gearing up to enter the working/adult world?

Also, has it been somewhat strange working in the same company as your fiancé?

P.S. All the best on your marriage and future endeavours :champagne:

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Okay, let’s do this

cracks knuckles


What prompted you to start a Bank?

Tom did :slight_smile: I was always more interested in making the machine that makes the thing, rather than whatever the thing actually is

And how are you planning to try to make yourself redundant?

I always struggled with this, but having a deadline (in this case my six week honeymoon) helps. Here’s what I posted in a company wide announcement last week:

That really helped and my diary and responsibilities immediately got lighter

FWIW, I haven’t been coding anymore for 18 months, so most of my responsibilities were around hiring decisions, coordination and staffing levels between teams, etc


What are you really excited for in the next 6 months? :slight_smile:

Meri starting and taking six weeks off to observe the “summer of Monzo” from a safe distance :slight_smile:


Are you ballin so big that you can now have a money gun?



What’s the most above and beyond tech related feature/process you think Monzo will get to?

I think our microservices platform has really paid off. It was a huge investment in the beginning, when it certainly would have been easier to build the bank as a quick rails or django app.

But now, we have over 600 microservices and over 100 production deployments each day by a dozen different squads. And most of them don’t interfere with each other or even have to know about each other.

I have seen this wrong previously and am very thankful to past us that we invested so much time into a platform that, at the time, was a little too big for us


What differences do you find between working at tech startups in Silicon Valley compared to in London?

I think it is harder for startups in London to take truly huge ambitions seriously. For better or for worse, a lot of entrepreneurs in Silicon Valley set out to have the largest possible impact. They want a billion users, global scale, a company to outlast all companies, etc… It all just goes without saying. In London, when we say “We are aiming for a billion users”, people often roll their eyes at us. I sometimes think of my role in the business as saying the outrageously ambitious things until everyone first repeats them and eventually believes them

Another thing I think is different is that employees in London don’t value startup equity as highly. In SF everyone knows somebody who was able to purchase a home or at least a car because they were one of the first several hundred staff of a huge tech firm that IPOd. In London there aren’t many examples of that, so people tend not to pay a huge amount of attention to that part of job offers


where is the honeymoon destination ?

We’ll see :wink: We have booked a one way flight to Vancouver and will then likely rent a campervan and tour down the pacific northwest. Towards the end of the trip we may stop by burning man (if we can get tickets)

It seemed a bit indulgent to spend much time planning the honeymoon when not even every aspect of the wedding is planned all the way through :wink:


Did you already have a system architecture in mind when you co-founded Monzo, or did you develop it with the initial team? Either way, what process did you go through to come up with the foundations on which Monzo was built?

The backend architecture was heavily influenced by Matt and Oli’s experience from Hailo. In particular the idea of very small microservices, using Go and using Cassandra as our primary database came from there.

The design of the platform arose from the following constraints

  • We didn’t know a huge amount about banking. We were very conscious that whatever functionality we’d build, we would probably have to rebuild a few times from scratch before we got it right. So we wanted it to be easy to rebuild entire components quickly

  • The people in the team knew how to make robust distributed service platforms already

  • We knew we didn’t want to do a huge “replatforming” once we hit scale, because that is very difficult to do without taking downtime (see for example Twitter’s famous “failwhale” phase; or from personal experience, in 2011/2012 Groupon had a similar period of lots of downtime)

  • We knew we had to go through a lengthy banking licence application before we could go live. At the time we didn’t know we were going to launch a prepaid card first

All of this led to our decision to invest heavily (well, as heavily as you can with 4 backend engineers) in building a distributed microservices platform


If you were to estimate, how much of the original code you wrote when Monzo was founded do you think is still in production today?

I wrote about 1/3 of the backend code for the first year (split fairly evenly with Matt and Oli). If I have time later, I’ll find out how many lines of code are still in production.

I stopped coding for the most part almost two years ago

I just had a look and discovered that I am still the #12 all time contributor to the Monzo codebase. But it looks like lots of people will pass that mark soon :wink: Here is my contribution history

For comparison, here is a graph of the contributions to our backend repository over the same time



Never had a cat or a dog. Dogs appear to be more useful, though

Pineapple on pizza?



Do you believe it’s possible to fully automate fraud detection or does human behaviour have too many variables for that to happen?

I think eventually it will be possible to “automate” most things, even things that are totally unthinkable today. So yes :slight_smile:


Baby mondo: What are the things you worked on initially before switching to a more managing role (when it was just the 4 of you until Monzo became big enough)?

Err, literally everything. One thing I’m particularly pleased about are the merchant emoji that we send along with push notifications. A surprising amount of work goes into maintaining that database. I initially built the feature to surprise/troll my coworkers. Who knew it would become such a hallmark of our brand!

Developer heart: Are you still working on development things yourself (actual line coding, not specs/architecture). If so, how do you decide this?

I’m not coding anymore, but I occasionally still give feedback on Pull Requests or RFC documents (RFC stands for Request For Comments) for systems that are either very important or that I find interesting

Redundancy: What are the things that still makes you a SPOF in the company (if there are any), apart from your seniority? Is there anything only you could do (give example) which are still on prod?

I haven’t been able to totally remove myself from making hiring decisions for a long time. I really struggle with that, because I find it hard to explain to other people exactly what I am looking for in hires. So I worry that our approach won’t scale beyond myself.

From a technical perspective, I don’t think I’m the single point of success for anything anymore


It would have to be between

  1. 90s point and click adventures. I learned how to read by playing Monkey Island, Indiana Jones and Day of the Tentacle. I pressed the space bar to pause the game literally on every sentence and then slowly worked out what was said (we didn’t have a soundblaster sound card until much later!). I also really like Kings Quest 5, 6 and 7, but I prefer the games where you can’t die

  2. Diablo, because I picked up programming to make a website about Diablo

I also got addicted to Counterstrike 1.4 and World of Warcraft as a teenager… I now stay away from those kinds of games, lest I relapse