Krzysztof is available for hire
Hire KrzysztofKrzysztof Mazur
Verified Expert in Engineering
Concurrency Developer
Location
Warsaw, Poland
Toptal Member Since
March 6, 2020
Krzysztof is a senior software engineer specializing in the Java ecosystem with strong experience in highly scalable, reliable architecture, and easy to maintain software. He's interested in using computer science theory and practice, finance, distributed systems, and machine learning throughout his projects.
Portfolio
Vodeno Technology
Terraform, Kubernetes, Google Cloud Platform (GCP), Elasticsearch, Spring, Akka...
Citi
H2, Oracle Database, OpenShift, Hibernate, Spring, ActiveMQ, Solace...
Goldman Sachs
Elasticsearch, Spring, Apache Spark, RxJava, Akka Streams, AngularJS...
Experience
Availability
Part-time
Preferred Environment
Software Architecture, Hibernate, Spring, Java
The most amazing...
...system I've developed is a highly distributed internal bank system that processed 2+ million events/day up to 1 million events/hour and served 80+ clients.
Work Experience
Solutions Architect
2019 - PRESENT
Vodeno Technology
- Supervised a squad of 7+ people, product architecture, and delivery.
- Created product architecture based on DDD, Event Storming, C4, ADR, and RFC. Analyzed, prepared, proposed, and tracked business, legal, and technical requirements and deliverables for the product.
- Integrated with an internal storage system and implemented measures to prevent potential failure modes.
- Identified and resolved security issues with the ITSec across the company.
- Conducted training on core computer science, distributed systems, SRE knowledge.
- Attended architecture board, and discussed and proposed solutions on the company-wide architecture.
- Initiated one-on-ones and mentorship programs with personal improvement plans as well as initiated and supervised agile methodologies processes for the squad.
- Wrote documentation for the squad and for several other squads as well as improved the existing ones and proposed automation when appropriate.
- Proposed and assisted with the implementation of the end-to-end hiring process.
Technologies: Terraform, Kubernetes, Google Cloud Platform (GCP), Elasticsearch, Spring, Akka, Apache Kafka, JavaScript, Java
Specialist
2018 - 2019
Citi
- Implemented Sev1 remediation during the first month that decreased whole platform startup 10x.
- Improved architecture design and multi-regional collaboration.
- Involved in the development of core components for high resiliency and COB/DR.
- Implemented main trade flow for FX forwards and swaps processing.
Technologies: H2, Oracle Database, OpenShift, Hibernate, Spring, ActiveMQ, Solace, TIBCO Enterprise Message Service (EMS), TIBCO, Java
Associate
2016 - 2018
Goldman Sachs
- Led the local team working on the internal product.
- Fixed many bugs in the software system that started with barely handling 1,000 events per week to 2+ million events per day with no downtime.
- Created and integrated with observability tools and dashboards like Zipkin and Grafana.
- Created custom management solutions for infrastructure state management, tracking, and recovery.
Technologies: Elasticsearch, Spring, Apache Spark, RxJava, Akka Streams, AngularJS, Apache Kafka, JavaScript, Java
Owner
2013 - 2015
Teligent
- Created an asset management solution for global H&M that stored, managed (videos and photos), and tracked the transformation of those assets (bitrate, file formats, splitting, etc.) for marketing campaigns globally using Java, Spring, and MongoDB.
- Created a global campaign management solution for global H&M which tracked details of the planning and preparation of the marketing campaigns Java, Spring, MongoDB.
- Implemented the eCommerce website for Wristy Technologies SA - a wristwatch startup.
- Implemented fiber-optic network construction planning and management system.
- Implemented custom cinema movies (in Poland) key encryption/decryption software for Chimney Group.
Technologies: Amazon Web Services (AWS), Android, Node.js, Hibernate, Spring, AngularJS, Docker, Groovy, PHP, Ruby, JavaScript, Java
Software Engineer
2012 - 2013
MMIGroup
- Implemented extensive API and integrations with Zoho Suite (e.g.with Comarch ERP Optima).
- Implemented two-way synchronization of the data from Zoho Suite to the Comarch ERP Optima system.
- Conducted training for the company's workforce on software development topics.
Technologies: SQL, Git, PHP, Swing, Java
Software Engineer
2011 - 2013
Sylogic
- Analyzed feasibility of the features of the SIRENE SIS II - new Schengen system for the Polish police headquarters.
- Performed security analysis and fixes for the TimeTrend watch retailer.
- Modified and deployed e-learning systems for the Polish Patent Office, Polish Livestock Genetics Institute, CH Beck, and Polish National Health Institution (NFZ).
- Wrote innovative management solution of pre- and post-graduation career tracking with CV builder for schools in Lubelskie province.
- Conducted presentations of the systems for investors.
Technologies: MySQL, PostgreSQL, SOAP, Hibernate, Spring, JSF, Jakarta Server Pages (JSP), JavaScript, Camel, PHP, ActiveMQ, Groovy, Java
Software Engineer
2011 - 2012
Silvercoders
- Led database model versioning, modification, and optimization.
- Analyzed performance and optimization of database queries, schema, and request round-trip times.
- Created a parser, analyzer, and mapper from XLS files to the internal system for truck delivery management and report generation.
Technologies: Apache Maven, CSS, JavaScript, HTML, PostgreSQL, Mercurial, Hibernate, XSLT, XPath, Cocoon, Spring, Java
Junior Java Developer
2010 - 2011
Vavatech
- Implemented various elements of a web application – front end and back end, along with several applet games.
- Conducted Jmeter performance analysis for the load analysis.
- Wrote seven games logic, server, and front end parts like Monopoly and card games.
Technologies: Apache Maven, Swing, Apache, MySQL, CSS, HTML, JSF, Hibernate, Spring, Java
Experience
H&M Marketing Campaign Management System
An H&M internal system to track marketing campaign processes. I developed a front end in HTML/SASS (Thymeleaf) and the back end in Java/Spring Boot. It integrated with the asset management system (also written by me) to approve, crop, and prepare technical specifications for assets and approvals for the next stages in the process in countries worldwide. The system consisted of multiple rich information dashboards for different roles in the system.
Education
2017 - 2020
Master's Degree in Computer Science
Warsaw University of Technology - Warsaw, Poland
2007 - 2013
Bachelor's Degree in Computer Science
Warsaw University of Technology - Warsaw, Poland
Certifications
APRIL 2019 - PRESENT
AI for Trading Nanodegree
Udacity
APRIL 2019 - PRESENT
Data Engineering on Google Cloud Platform Specialization
Coursera
MARCH 2019 - PRESENT
Architecting with Google Cloud Platform Specialization
Coursera
MARCH 2019 - PRESENT
Deep Learning Specialization (deeplearning.ai)
Coursera
FEBRUARY 2019 - PRESENT
Deep Reinforcement Learning Nanodegree
Udacity
AUGUST 2018 - PRESENT
Deep Learning Nanodegree
Udacity
JULY 2018 - PRESENT
Biases and Portfolio Selection
Coursera
JULY 2018 - PRESENT
Investment Strategies and Portfolio Analysis
Coursera
JULY 2018 - PRESENT
Portfolio Selection and Risk Management
Coursera
JULY 2018 - PRESENT
Global Financial Markets and Instruments
Coursera
JUNE 2018 - PRESENT
Introduction to Financial Markets
Coursera
MAY 2017 - MAY 2019
AWS Certified Developer - Associate
AWS
MAY 2017 - MAY 2019
AWS Certified Solutions Architect - Associate
AWS
APRIL 2017 - PRESENT
Functional Programming in Scala and Spark (5 course specialization)
Coursera
MARCH 2016 - PRESENT
Concurrency Performance for Java 8 Course (Heinz Kabutz)
JavaSpecialists.eu
MARCH 2016 - PRESENT
Machine Learning
Coursera
Skills
Libraries/APIs
Cocoon, Node.js, Akka Streams, RxJava
Tools
Elastic, Git, Apache, Apache Maven, Mercurial, ActiveMQ, TIBCO Enterprise Message Service (EMS), Terraform
Frameworks
Spring, Hibernate, JSF, Swing, Camel, Jakarta Server Pages (JSP), AngularJS, Apache Spark, Akka
Languages
Java, JavaScript, HTML, CSS, XPath, XSLT, PHP, SQL, Groovy, Ruby
Paradigms
Web Architecture, Clean Code, Design Patterns
Storage
MySQL, PostgreSQL, Elasticsearch, H2
Platforms
Amazon Web Services (AWS), Google Cloud Platform (GCP), Apache Kafka, Docker, Android, OpenShift, Oracle Database, Kubernetes
Other
Concurrency, Software Architecture, SOAP, TIBCO, Solace
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