Andrey Breslav (photo)

Andrey Breslav: A short bio

  • 2018-2020 - President of the Kotlin Foundation

  • 2018-Now - Advisory Board Member at SE Dept, St. Petersburg State University

  • 2018-2020 - Co-founded JSpecify (on behalf of JetBrains)

  • 2017-Now - Co-founder at

  • 2010-2020 - Lead Language Designer and Project Lead for Kotlin at JetBrains

  • 2010-2014 - Member of Java Community Process JSR335 Expert Group: Project Lambda

  • 2004-2013 - Lecturer and the ITMO University, PhML 239 and AMSE

More on my LinkedIn Profile

Ex-Lead Designer of Kotlin. I may not be responsible for all the good stuff in the language, but all the shortcomings are 100% my oversight. I was in charge of the development of Kotlin 1.0-1.4: had the last say in all design decisions, wrote a big portion of the compiler, managed the team, and was the main spokesperson for Kotlin. Held the ceremonial office of the President of the Kotlin Foundation and served as the Lead Langauge Designer on the Kotlin Language Committee. Handed over all my duties and left JetBrains in 2020. More on how and why. This video

Cofounder of Together with Olga Kitaina we started the company in 2017 and grew it to be one of the biggest mental health platforms in Eastern Europe with close to 1000 therapists and thousands of new clients joining every month. Some details on the company.

Public Speaker. I love sharing my perspective and being on stage. It was my privilege to speak at TEDx, KotlinConf, Google I/O, Devoxx, OSCON, Java One, JVM Language Summit, and many other great events. My core topics are programming languages, leadership, mental health, and soft skills. Videos of some of my talks can be found here.

Educator. I did a fair bit of teaching at the university and high school levels. Recorded two online courses: one on Kotlin, with Svetlana Isakova, and one on Mental Health, with Natalia Kiselnikova (in Russian).

Some recollections

I was born in 1984 in Leningrad, USSR (soon to become Saint Petersburg, Russia). Went to ФМЛ 239, if you know what I mean. Did my BSc and MSc in Applied Math and Computer Science at the ITMO University in Saint Petersburg. As a PhD student, did internships with the University of Tartu (Profs. Marlon Dumas and Varmo Vene) and Microsoft Research (with Dr. Ethan Jackson). Dropped out of my PhD program at ITMO to work on Kotlin full time.

Andrey Breslav (childhood photo in black and white)
An opening screen of Microsoft QuickBASIC for MS-DOS

My first encounter with programming was sometime around 1995 or 1996, with a Nixdorf-branded 80286 machine, Microsoft QuickBASIC for MS-DOS on a floppy disk, and a few pages on BASIC from a very old Soviet high school textbook. I didn't know that numbering every line was optional in modern BASIC, so my first programs were all line-numbered. The first program I wrote asked the user for a password in a loop until the hard-coded string matched the input. I didn't get it right from the first run, of course, and it looped forever. Oblivious of Ctrl+C, I could only Ctrl+Alt+Del, and all my precious code was lost. This is how I started learning the Ctrl+S reflex.

When I got my first Pentium computer around 1997 or so, my uncle gave me a book on Borland Delphi, and over the next 5-7 years, I learned every corner of the Object Pascal language, the VCL library (thanks for the sources, Borland!), and the Delphi integrated environment. I think Anders Heilsberg, the mastermind behind Delphi and many other great programming systems, may have influenced me the most as a language designer and programmer, although we never met in person and only had a brief email exchange in 2010 while I interned at Microsoft Research.

If you ever find this book in print, give me a wink, I lost my original copy and would really like to have it again: Программирование в среде Delphi: Пер. С англ. /Джефф Дантеманн, Джим Мишел, Дон Тейлор. – К.: НИПФ «ДиаСофт Лтд. », 1995. – 608 с. ISBN 5-7707-9149-7

The cover of the first book on Delphi that I learned so much from

I took up teaching when I was a third year student at the university. Started with highschool programming classes, then did university courses and AMSE under Nikolay Pultsin and Andrei Ivanov (then at Borland, now a senior executive at JetBrains).

The logo of Borland

It so happened that my first employer as a programmer was actually Borland, although I never worked on Delphi. Our team worked on Together for Eclipse, the UML tool. I was quite a bit into UML, metamodelling and Generative Programming stuff at the time. It took me some time to see through the hype, but generative programming naturally lead to Domain-Specific Languages which I studied in-depth for a number of years, up until 2010 when I joined JetBrains to start Kotlin.

Using the old logo because this is what it was when I joined. The first design ideas for Kotlin were written down on a whiteboard the very day I came in for a "get to know each other" conversation. It wasn't much of an interview, felt more like a discussion. I started in June 2010, but made a break to do a previously planned internship with Microsoft Reseach. Picked up in the fall of 2010. We worked a lot with Max Shafirov on the initial design, the four of us, together with Dmitry Jemerov and Alex Tkachman, started working on the compiler and the initial IDE support.

The logo of JetBrains from 2010
The first logo of Kotlin with a colorful kettle

The name Kotlin did not exist for another year or so. The project was codenamed "Jet" and it can still be seen in the git history. The trademark fro "Jet" was taken so we agonized over a new name up until almost the very deadline for the public announcement at JVM Language Summit in 2011. Dmitry Jemerov came up with the name Kotlin. It's an island in the Baltic sea near Saint Petersburg, you couldn't quite see it from our office but it was not far. We picked up on some inaccurate Wikipedia article of the time and thought the work meant "kettle" in Swedish, that's why the early logo has a kettle in it. We also called it "Project Kotlin" to emphasize that it was just a code name that could be changed later. But nobody ever got around to reconsidering the name. Picking names is just too hard.

This is proof that I indeed had a beard when I presented Kotlin at StrangeLoop in 2011. The video from the very first presentation, at JVMLS the same year, seems to have been lost but the beard was there, too. Slides from the JVMLS talk can be found here.

If you are at a loss about beards and programming languages, here's an explanation for you.

A frame from a talk I gave at StrangeLoop 2011, showing me with a beard
A drawing by John Rose of a lambda and an Escher's cube for JVM Language Summit 2011

I represented JetBrains in the JSR 335 Expert Group led by Brian Goetz. It was a lot of fun and a great honor. We discussed the design of lambda expressions, SAM conversions, default methods, and method references for Java, as well as the corresponding library changes.

The mailing list discussions were, perhaps, more important, but I enjoyed the in-person meetings in Santa Clara attached to the JVM Language Summit. A lot of insights from Brian Goetz, John Rose, Joshua Bloch, Doug Lea, and others. It surprised me at first how these very accomplished people treated me as an equal and seemed genuinely interested in hearing my opinions, and I try to follow their example.

Later, in 2018, when it turned out that Kotlin's idea of null safety was in high demand but there was little chance to get it into Java proper any time soon, we collaborated with folks over at Google (primarily, Kevin Bourillion and Kevin Bierhof, if memory serves) and started JSpecify. I'm happy to see that many companies, including Oracle, have joined this initiative over time.

Kotlin was initially designed for server-side and desktop applications on the JVM proper. Android wasn't on our radar in 2010. It was the early days of smartphones, after all.

In fact, we only started testing anything against the Android toolchain after a few embarrassing bugs were reported by early adopters. Here's the first report in a forum thread from 2012 where all I could say was "Kotlin should theoretically work with Android".

At some point, I realized that Android could be a very good market for Kotlin because there were a lot more new and short-lived projects, and picking up a new language is easier when you start from scratch.

We invested heavily into Android compatibility, developers loved Kotlin, and eventually, Google announced official support on Android in 2017 and then made Kotlin the preferred language in 2019.

A frame from Google I/O 2017 Developer keynote when Kotlin was announced
Co-founders of Alter: myself and Olga Kitaina

I started my own therapy in 2015 and was excited about the results. I wanted more people to use this wonderful tool to improve their lives. I started looking for ways to help this happen and ended up talking to everyone I knew and their friends about therapy. Soon enough I was introduced to Olga Kitaina, a psychologist, who had recently started working on a mental health startup. We joined forces in June 2017, and launched an MVP in November.

I oversaw the technical side of things, Olga was the CEO and the expert in therapy. We ran the business side of things together, discussing all significant decisions and nudging each other forward.

We ended up building one of the biggest mental health platforms in Eastern Europe, with about 1000 therapists and more than 2000 clients joining every month.

Over the years, especially as I gave up teaching, public speaking became the primary means of my non-technical self-expression. Around 2019 I focused some energy on raising awareness of the topics I care very deeply about:

  • Mental health and especially impostor syndrome and burnout;

  • Emotional awareness, especially in the context of science-minded world view;

  • Gender equality issues and effective means to achieve it.

You can find videos of my talks on this page.

A word cloud from a conference talk with "inspiration", "fun", "learn", "knowledge" and "kotlin" as the biggest words