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David Krentzlin

Keep learning. Show up. Do the work. Finish strong.

With 20 years in the field, I eat, sleep, and breathe code. I know how to approach complex systems and build components that meet today’s demands. I am comfortable being both a leader and a follower.

In the end, it’s about people, communication, and relations - occasionally about technology.


All the projects I have on GitHub are for my personal educational purposes. That’s the usual disclaimer to say that they’re in development and even though I try to keep the main branch functional at all times, it may contain code that’s incomplete or wrong.

I’m working on the following projects:

  • cl-braces implementation of a compiler and vm for golang inspired language - Common Lisp
  • 1brc Solution for the 1 billion row challenge, to see if I can solve it in acceptible time in Common Lisp
  • cl-dns Implement DNS in a weekend - Common Lisp
  • agol Conway's game of life - Common Lisp
  • braces a scheme compiler and virtual machine - Rust


I’m a backend guy and have worked on many services and platforms during my career.

I think it’s fair to say that I’m much better at building infrastructure, platforms and developer tooling, than user-facing products. As it’s quite common in our industry, I’ve gone into management, stayed there for a while, and circled back into an IC role. I have learned a ton in each of those areas and like to think that this made me overall well-rounded. I enjoy learning new things, and exploring new areas, which I can approach with a beginner's mindset. I found that this keeps me grounded, humble and engaged.

Head over to my CV for all the details, or look at my three most recent positions here:

  • Senior Software Architect at New Work SE, supporting the cloud platform team.
  • Tech Lead at Hive Technologies, supporting the delivery & end-customer experience team.
  • Team Lead Architecture at New Work SE, leading the API platform team that built and operated the GraphQL platform.


I gave talks on various local meetups. In 2018 I gave a talk at the GraphQL EU on how my team built our GraphQL platform.

Get in contact with me

David Krentzlin's LinkedIN David Krentzlin's Xing David Krentzlin's Twitter

Popular repositories

  1. braces braces Public

    A toy scheme compiler and VM in rust. This is my take on crafting interpreters.

    Rust 7

  2. rb-graphql-template rb-graphql-template Public

    Forked from redbubble/rb-graphql-template

    A template for Scala HTTP GraphQL services.

    Scala 3

  3. go-braces go-braces Public

    A programming language and compiler implementation for PL nerds

    Go 2

  4. cl-braces cl-braces Public archive

    An, in progress, compiler and virtual machine for a subset of golang

    Common Lisp 1

  5. 1brc 1brc Public

    1 billion row challenge in Common Lisp

    Common Lisp 1 1

  6. chicken_sendfile chicken_sendfile Public

    Scheme 2