Marek is available for hire
Hire MarekMarek Kadek
Verified Expert in Engineering
ZIO Developer
Location
Vienna, Austria
Toptal Member Since
February 28, 2015
Marek is a talented developer with a focus on back-end and solid desktop development experience. He emphasizes clean code and solid architecture. Marek is experienced working with remote Scrum teams and understands the importance of good communication. He loves both functional programming and good object-oriented design and enjoys creating reactive applications.
Portfolio
Upstart Commerce
Scala, Akka, Elasticsearch, ZIO, OpenTelemetry
Chili Piper
Scala, Akka, MongoDB, Redis, ZIO
Cisco
PostgreSQL, Cassandra, Helm, Kubernetes, Akka HTTP, Scala
Experience
Availability
Part-time
Preferred Environment
Git, IntelliJ IDEA, Visual Studio Code (VS Code)
The most amazing...
...thing I've coded is a highly scalable and extensible messaging platform based on Ejabberd, utilized through many apps.
Work Experience
Tech/Team Lead
2021 - PRESENT
Upstart Commerce
- Led the development of an advanced, configurable, and business-focused search engine to replace the expensive legacy engine while maintaining and extending all existing functionality.
- Spearheaded the development of a complete overhaul of the old search platform in favor of a new one across 20+ microservices, leading to 5-10x throughput and halving the average latency.
- Designed and developed the architecture for business-relevant metric collection and its exposure via dashboards.
- Mentored new Scala engineers and performed code reviews and introductions to functional programming.
Technologies: Scala, Akka, Elasticsearch, ZIO, OpenTelemetry
Senior Software Engineer
2019 - 2021
Chili Piper
- Created and exposed internal functionality as an API service for our clients and helped them with automated integration.
- Performed the integration of various services such as Stripe and Intercom.
- Redesigned the back-end platform to support multiple licenses and new products. Implemented the rollout of Freemium with custom onboarding flows.
- Led back-end development of the company's new product: Chilipiper Inbox.
- Helped with infrastructure and canary deployments, monitoring, and post mortem investigations.
Technologies: Scala, Akka, MongoDB, Redis, ZIO
Scala Software Engineer
2017 - 2018
Cisco
- Worked on a microservices platform built as a Kubernetes operator accompanied by Cisco proprietary language and tooling.
- Implemented a compiler from a proprietary language to the target language.
- Added a Cassandra-backed storage layer for underlying services.
- Collaborated on the infrastructure, deployments, and monitoring of our cluster.
- Reviewed code and introduced new team members to Scala.
Technologies: PostgreSQL, Cassandra, Helm, Kubernetes, Akka HTTP, Scala
Remote Freelance Software Engineer
2017 - 2017
Toptal Clients
- Created new services and helped migrate existing ones.
- Migrated the old Cassandra event store to the latest schema, and wrote an app to find and replay missed events.
- Optimized a PostgreSQL database for slow queries, index issues, etc.
- Investigated integration with Chatfuel.
- Integrated RiveScript with Twilio and Facebook.
- Optimized the messaging platform and its reliability.
- Migrated services between Play's major versions.
- Implemented a billing service and accompanying integrations.
Technologies: Amazon Web Services (AWS), Elasticsearch, Heroku, Cassandra, Redis, PostgreSQL, AMQP, SBT, Play, Akka, Java, Scala
Architect, Developer
2015 - 2017
Spring
- Created a foundation library for working with OrientDB in a very composable way (merging sessions, optimizing round trips to database, etc.).
- Implemented a library to enable easily composable and testable modeling of processes in Spark.
- Implemented the OrientDB live streaming library, enabling developers to make asynchronous live queries that adhere to reactive streams specification. The project was open sourced.
- Completed a detailed evaluation of messaging systems, including Pusher, PubNub, and Ejabberd.
- Impemented various plugins for Ejabberd in Erlang/Elixir.
- Implemented various REST APIs as endpoints for Ejabberd's plugins.
- Implemented a continuous delivery/continuous integration/build pipeline via SBT.
- Implemented custom SBT plugins for the team.
- Architected back-end and front-end for various projects in Scala and Scala.js.
- Contributed to various open source technologies we were using across all layers, from front-end libraries to the database layer.
Technologies: Elixir, Erlang, Ejabberd, Spark, OrientDB, Reactive Streams, Akka, Play, Finch, Finagle, SBT, Scala.js, Scala
Software Engineer
2013 - 2015
ERNI Consulting AG
- Helped develop a client-server application for control, monitoring, and automation of chemical analysis (titration, pH, measurement, voltametrics, etc.) by using analytical instruments.
- Created and implemented the concept of licensing a large, feature-rich application using Wibu Systems.
- Helped with the introduction of Rx into an application layer and the transformation of several software parts to be more event-driven and reactive.
- Refined and refactored several core parts of a large codebase to minimize existing technical debt.
- Designed and developed various separate components and technical documentations.
- Assessed and tested Xamarin Cloud for a mobile team.
- Introduced patterns for mobile developers to improve testability.
- Developed an internal ASP application to allow clients to easily translate resources for Android and iOS applications.
- Helped to estimate a few potential projects.
- Developed several proofs of concept to demonstrate potential functionality and design to possible future clients.
Technologies: Xamarin, Hudson, NuGet, NUnit, Git, NHibernate, Microsoft SQL Server, Windows Communication Foundation (WCF), Windows Presentation Foundation (WPF), Rx, .NET, C#
Android Developer
2013 - 2013
Logamic s.r.o.
- Developed on both the back-end and front-end, creating a reusable scratch card-like lottery system for a large job fair.
- Created an application for specific types of Android phones to replace the home screen, designed for old or visually impaired people.
Technologies: Git, Java, Android
Programmer Analyst
2011 - 2013
Adhertec s.r.o.
- Created a fully autonomous system reminding and notifying patients to take their required medicines via automated SMS or prerecorded VoIP calls.
- Created an intranet for a large corporation to automate some administrative tasks such as managing, scanning, and storing invoices.
- Developed an algorithm enabling oncology patients to search among doctor-verified publications.
- Implemented a visualization of various medical facilities on maps using Google Maps API to help oncology patients locate the facilities.
- Created a layer for the company's framework to enable clients to easily compose and hot swap components on a live website.
- Created a reusable system building and maintaining questionnaires for the patients of selected doctors.
- Developed an automatic processing system for questionnaire data to visualize the results in the form of various graphs.
- Developed and maintained internal systems making the discussions between doctors and their patients easier.
- Created an internal application improving the process of text translation between clients and a company.
- Consulted various clients for requirements.
- Assessed and estimated projects. Identified critical sections of upcoming projects.
- Maintained a legacy codebase to handle the complicated business logic of one specific client.
Technologies: Web Services, Subversion (SVN), MySQL, JavaScript, PHP 5, Windows Communication Foundation (WCF), Windows Presentation Foundation (WPF), C#
Web Developer
2010 - 2011
ELBIA s.r.o.
- Created back-ends for various websites and services.
- Maintained a company's custom framework and CRUD generator, making the initial phase of new projects easier by removing the need to write boilerplate code.
- Improved and fixed several problems related to data processing on one of Slovakia's largest sites for the visualization of allergen concentration.
- Developed a REST service for a web hosting company with a rich set of functionalities, providing an API for all possible user actions.
- Created a reusable framework to pair up invoices with bank statements, supporting various payment methods.
Technologies: Web Services Description Language (WSDL), SOAP, Web Services, Subversion (SVN), MySQL, PHP 5, JavaScript
Experience
Cassabin - Purely Functional, Async Non-blocking C* Driver
Purely functional, asynchronous non blocking Cassandra driver that speaks binary protocol (CQL) to Cassandra.
Scala Crawler
https://github.com/KadekM/scrawlerWeb crawling and scraping using fs2 streams. Support sequential/parallel crawling and various browsers. Designed in a tagless final.
Scalac Plugin - Compile-checked TODOs
https://github.com/KadekM/scala-forced-todoScala compiler plugin to check expiration of TODO annotations at compile time.
Scalatags Observable VDOM
https://github.com/KadekM/scalatags-vdom-observableSupport for Rx Observables in Virtual DOM from Scalatags.
Open Source Contributor
https://github.com/KadekMA few of my open source contributions (Akka.NET, Scala Rx, etc.) and personal projects (Scala Crawler, OrientDB Reactive Streams, etc.).
OrientDB Scala Streams
https://github.com/KadekM/orientdb-scala-streamOrientDB Scala reactive-streams (Akka streams) library for non-blocking and live queries.
Visit to Valve Corporation in Seattle
In the summer of 2013, I was invited to Valve HQ in Seattle to help them improve their new upcoming version of Counter Strike.
Server Side Anti-cheat Plugin
A plugin for Counter Strike servers that detects players with invalid DirectX settings that give them unfair advantages. The plugin was used worldwide at tournaments for several months.
Starcraft AI Robot
I developed a fully automated AI robot to participate in a tournament against other robots. The robot uses various heuristics (such as observing the enemy, assessing the strength of the enemy army, and determining enemy strategy) and advanced mechanisms to determine current best action.
Visual Navigation for Acrobat with Android Using Camera
The goal of this project was to set up and code an Arduino robot that would navigate through a maze by recognizing different colors and shapes using an external camera. The camera is provided by an Android phone that is physically attached to the robot. The Android and robot communicate via Bluetooth. The robot uses a neural network library (Neuroph) to train and recognize shapes and colors.
SAT Solver
An application to solve a boolean satisfiability problem. It is written in C++ and optimized for performance.
3D Terrain Editor
An application for terrain generation with nice shaders and a wide range of features.
Remote PC Control
An application that allows users to control their PC remotely by Android smartphone.
Skills
Languages
Java, Java 8, Scala, C#, GraphQL, Erlang, SQL, F#, JavaScript, PHP 5, Web Services Description Language (WSDL), Elixir, Haskell
Libraries/APIs
LINQ, Slick, Akka Streams, Scalaz, Scala.js, AMQP
Paradigms
Object-oriented Design (OOD), Functional Programming, Continuous Integration (CI), Distributed Programming, Agile Software Development, Reactive Programming, Concurrent Programming, Test-driven Development (TDD), Design Patterns, REST
Other
ZIO, Ejabberd, XMPP, Reactive Streams, Web Services, SOAP, Windows Communication Foundation (WCF), Finch, Akka HTTP, Shapeless, Machine Learning, OpenTelemetry
Frameworks
Apache Spark, Play Framework, .NET, Rx, Akka, Windows Presentation Foundation (WPF), NHibernate, NUnit, Finagle, Play, Spark
Tools
GitLab, Travis CI, GitHub, Bamboo, SBT, Vim Text Editor, Subversion (SVN), Git, NuGet, Hudson, IntelliJ IDEA, Visual Studio, Helm, Kafka Streams
Platforms
Docker, Windows, Linux, Apache Kafka, Android, Xamarin, Heroku, Amazon Web Services (AWS), CoreOS, Kubernetes, Visual Studio Code (VS Code)
Storage
PostgreSQL, OrientDB, Cassandra, Elasticsearch, MySQL, Microsoft SQL Server, Redis, MongoDB
Education
2010 - 2013
Bachelor's Degree in Applied Informatics
Comenius University - Bratislava, Slovakia
Certifications
SEPTEMBER 2014 - PRESENT
Certified Professional for Software Architecture (F-level)
iSAQB
JANUARY 2014 - PRESENT
Programming in C# Specialist
Microsoft
JANUARY 2014 - PRESENT
Microsoft Certified Professional
Microsoft
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