Malcolm Matalka, Developer in Stockholm, Sweden
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Malcolm Matalka

Verified Expert  in Engineering

Software Developer

Stockholm, Sweden
Toptal Member Since
December 7, 2020

Malcolm has been developing software since 2006. He has worked for startups and large banks and freelanced across a range of languages and technologies. After focusing primarily on back-end development, he broadened his expertise to include front-end development in 2015. Malcolm has been the technical lead on multiple projects in the financial, music streaming, and medical device industries.



Preferred Environment

PostgreSQL, OCaml, TypeScript, Python, FreeBSD, Linux

The most amazing...

...front-end and back-end software I've developed is for a system that analyzes DNA sequences for cancer. Scientists designed the analyses; I built the software.

Work Experience

Senior Software Engineer (Remote Contractor)

2017 - PRESENT
Abiogenesis Computer Systems Lab
  • Served as the primary developer for a next-generation, sequencing-based medical device and the first of its kind to receive FDA approval.
  • Led the development of front- and back-end components and several initiatives to simplify the existing code and improve stability. Multiple customers noted the stability of the product.
  • Collaborated with the QA department to improve their understanding of the system, improve their testing, and reduce testing time, thereby reducing the time to market.
Technologies: TypeScript, Angular, Django, Python

Senior Software Engiener

2015 - 2017
Spotify AB (Sweden)
  • Led the design and implementation of a Google Cloud-based backup system, enabling teams to move their services from on-premise to the cloud.
  • Improved operational confidence and reduced operational mistakes while serving as the technical lead for the team developing operational tooling for Cassandra.
  • Performed on-call duty for database operations. Our group served as the database experts and second line for all company databases, supporting customer-facing services during database outages.
  • Co-led the group developing new technical interviews for the department.
Technologies: Java, Apache Cassandra, Google Cloud, Python

Senior Software Engineer

2012 - 2015
Klarna AB (Sweden)
  • Served as the core developer of a horizontally scalable, highly available, purchase taking system designed to address operational concerns around Black Friday and Christmas shopping seasons.
  • Developed a data replication system for sharing data between active-active nodes between data centers, thereby improving availability.
  • Played a key role as the technical lead for the development and DevOps team of around 10 people and performed on-call duties.
Technologies: Ansible, Chef, Riak, Erlang (OTP), Erlang

Software Developer

2009 - 2011
Institute for Genome Sciences
  • Developed ParaMugsy, a distributed, multiple whole-genome aligner, allowing scientists to perform analysis more quickly and across more whole genomes than previously possible.
  • Led back-end development for CloVR, a virtual machine-based genomic analysis appliance, allowing scientists to transparently perform their analysis in the cloud, which reduced turnaround time and improved reproducibility of biological analyses.
  • Conducted performance, stability, and scalability testing for internal cloud deployment, providing academic institutions access to a reliable system and free service for performing computations.
Technologies: Amazon Web Services (AWS), Virtual Machines, Cloud, C++, Twisted, Python

Software Developer

2006 - 2008
Bear Stearns
  • Managed the process of merging new releases of third-party tools with internal modifications to keep the business on the latest releases, including security updates.
  • Led testing and evaluation activities for the transition to Azul JVM, significantly improving the performance and observability of our product by purchasing new hardware.
  • Worked on the team that developed a new derivatives trading platform for internal customers, which helped to grow certain lines of business.
Technologies: Java

With YAML omnipresent as an application config, seeing the difference between two YAML files can be difficult. YAML Diff is a web application that runs entirely in the browser. It normalizes the YAML, allowing it to be meaningfully compared. Because it runs entirely in the browser, it is safe to use, even with sensitive content.

Master Password Generator
With password managers quite common, one still needs to set a password for the password manager. This password generator uses the well-known xkcd algorithm to generate passwords that are easy to remember but also secure. The password generator runs entirely in the browser, making it safe to use despite the content being so sensitive.
2008 - 2010

Master's Degree in Bioinformatics

Johns Hopkins University - Baltimore, MD, USA

2001 - 2006

Bachelor's Degree in Computer Science

Worcester State College - Worcester, MA, USA


GitHub API


Chef, Ansible, NGINX, Amazon CloudFront CDN


Django, Angular, Twisted


FreeBSD, Amazon Web Services (AWS), Linux, Raspberry Pi


Python, OCaml, Python 3, Erlang, Erlang (OTP), TypeScript, Java, C++, JavaScript, YAML


PostgreSQL, Riak, Google Cloud, Amazon S3 (AWS S3)


Automated Testing, REST


Software Development, Distributed Systems, Cloud, Apache Cassandra, Full-stack, Ajax, Code Review, HTTP, Biology, Research, Virtual Machines, Caching

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