Radek Ostrowski - Freelance Ethereum Developer for Hire

Blockchain Consultant

2018 - PRESENT

StartOnChain

Engaged with clients wanting to enter the blockchain space, especially in the Ethereum ecosystem.
Won a prize for my "Time Locked Wallet" demo project in ConsenSys - uPort Blockchain and Identity Hackathon.

Technologies: Blockchain, Ethereum, Smart Contracts

Blockchain Engineer

2018 - 2018

Fan Hero (via Toptal)

Provided consultancy on Ethereum.
Researched the use of permissioned blocks.
Investigated transferring tokens without ether.
Prototyped a token contract.

Technologies: Ethereum, Solidity

Ethereum/Solidity Developer

2018 - 2018

Kryptonex LLC (via Toptal)

Helped to integrate Ethereum and ER20 tokens into an exchange that is currently being built. It included address generation, token listing, and basic wallet operation related to ether and tokens using Web3.js.

Technologies: Solidity, Ethereum, Web3.js

Big Data Engineer

2017 - 2018

Commonwealth Bank of Australia

Provided consultancy on big data technologies and data science.
Architected and designed scalable solutions.
Developed solutions mainly with Apache Spark and Scala.
Employed machine learning techniques to maximize profit.
Led a team to victory in an internal hackathon – developed a Slack bot for knowledge discovery, deployed on AWS.

Technologies: Apache Spark, Scala, Machine Learning

Big Data Engineer

2016 - 2016

Taulia, Inc. (via Toptal)

Designed and built a new generation of Taulia’s data analytics platform.
Effectively processed financial data and extracted useful information both in batch and real time.
Built the platform in Scala, Spark Streaming and SQL, Cassandra, Kafka, Docker, and Redshift, running on Kubernetes on AWS.

Technologies: Spark, Scala, Kafka, Cassandra, Docker, Kubernetes, AWS, Redshift

Big Data Engineer

2015 - 2016

Method Mill

Helped integrate various data sources on a large scale.
Built a pipeline from MySQL to Amazon Redshift.
Created a syncing tool for Amazon S3.

Technologies: Spark, Scala, Akka, Docker, AWS (mainly S3, Redshift, and Redis), MySQL

Big Data Engineer

2015 - 2015

Max2, Inc. (via Toptal)

Helped design and build a community-powered venue discovery platform offering personalized recommendations, planning with friends, and curated and real-time information.
Used SparkSQL with DataFrames for data ingestion and Spark Streaming and MLlib for analytics.
Coded in Scala with Akka and Kafka and run on Mesos.

Technologies: Spark, Scala, Kafka, Akka, Mesos

Senior Developer/Docker Evangelist

2015 - 2015

Tesco Bank

Introduced Docker to the development environment.
Helped improve the CI pipeline.
Extended the credit card portal.
Improved the user journey experience for a loan portal.

Technologies: Java, Spring Framework, Cucumber JVM, Git, Docker

Big Data Engineer

2015 - 2015

Expedia, Inc.

Helped to automate the build and run process.
Prototyped with Apache Spark.
Updated existing Hive and MapReduce workflows.

Technologies: Hadoop Ecosystem, Apache Spark, Git, Chef, Azkaban, Jenkins

Senior Software Developer/Team Leader

2013 - 2015

Sony

Built a production RESTful Java web service for Sony devices and platforms mainly for Sony PS4 and 4K-TV handling hundreds of thousands of transactions.
Developed on top of Spring Framework and Cassandra.
Offered authentication and authorization capabilities based on OAuth2.
Focused on quality of the code by employing unit testing with 100% code coverage, BDD with Cucumber, code reviews with GitHub pull requests, and Jenkins.
Produced a project collecting, analyzing, and visualizing statistics from Sony devices. The data is stored in Amazon S3 and processed using Hadoop (MapReduce and Hive). The data collection server and the BI portals are Java based (Spring MVC and REST). I secured the access to the web services (by extending Spring Security) and the relational databases. Other technologies used include Apache Karaf (OSGi) and Maven.
Worked on the “One Account – All Sony” global unified accounts integration project for Playstation and other devices.
Led a team of three in Brussels and collaborated closely with the rest of the team in San Diego.

Technologies: Java, Scala, Spring Framework, REST, Cucumber, OAuth 2.0, Hadoop, Hive, Amazon EC2 and S3, Jenkins, GitHub, Splunk

Senior Developer

2012 - 2012

DeltaDNA (GamesAnalytics)

Tackled the challenges of real-time data collection, predictive analytics, data measurement, and user engagement for the millions of online and mobile computer game sessions, personalizing the user’s gaming experience and increasing retention and revenue as a result through optimized game design and individually targeted in-game messaging.
Designed, developed, and provided continuous updates and enhancements of new features as part of an Agile in-house development team for the platforms and mobile SDKs.

Technologies: Java, Spring Framework, REST, VoltDB, Hadoop, Hive, Android, iOS, AWS

Applications Consultant

2006 - 2012

EPCC (University of Edinburgh)

Led “Work Package 3: Test, Delivery, and Support” from start to finish in a data-intensive research project for the EU which was rated Excellent.
Designed and implemented the test platform, new software components based on Java, REST, Spring, Hibernate, and HDFS and extended existing software components such as OGSA-DAI during the lifespan of the project.
Worked on a Master of Science in High Performance Computing, “test infecting” the students by lecturing and leading tutorials on unit testing and extreme programming and Agile methods; also created and gave a lecture on cloud use cases.
Developed a RESTful presentation layer based on Jersey for the software program OGSA-DAI.
Designed and developed an iPhone application for the UK National Supercomputing Service.
Fixed performance problems involving CUDA, C, JNI, and Java code and improved its graphical user interface via a spinout company.
Contributed to the project investigating the usage of Hadoop/MapReduce and clouds (Amazon EC2/Eucalyptus) for the analysis of post-genomic data.
Enabled the integration of the UKQCD community with the International Lattice Data Grid by implementing a web service layer in Java.

Technologies: Java, REST, Spring, Hadoop, AWS

Topcoder/ConsenSys - uPort Blockchain and Identity Hackathon (Development)

https://github.com/radek1st/uport-time-locked-wallets

Designed and implemented Ethereum dApp, which won a prize in the hackathon. It consists of smart contracts and a web front-end, and can be used for time locking Ethereum and ERC20 tokens. The dApp could be used for crypto gifts and vesting.

My Perfect Weather - IBM Spark Competition (Development)

http://devpost.com/software/my-perfect-weather

I designed and built the web service that became a winner of the Grand Prize and the Fan Favourite award in the IBM Sparkathon.

Dipping into the Big Data River: Stream Analytics at Scale (Development)

https://github.com/radek1st/BigDataRiver

I presented my project at the biggest data conference in Australia. Recorded talk is available here:
http://data.yowconference.com.au/profile/?id=radek-ostrowski

Kaggle - Data Science Competitions (Development)

https://www.kaggle.com/radek1st

My rankings demonstrate my ability to compete with the world's best data scientists:
* Top 6% (100/1984) in Expedia Hotel Recommendation
* Top 9% (84/979) in Outbrain Click Prediction

iWisps - IBM Spark Competition (Development)

https://devpost.com/software/iwisps

A fast, scalable, and portable local business recommender microservice powered by Apache Spark. I designed and built the project that became a winner in the IBM Spark competition and received a 'big check' at the IBM event in NYC.

Scala for Data Science (Development)

http://www.amazon.com/Scala-Data-Science-Pascal-Bugnion/dp/1785281372

I was a technical reviewer for the book.

Contributions to Spark Notebook (Development)

https://github.com/andypetrella/spark-notebook/pull/191

Created a demonstration of anomaly detection in Spark using Spark SQL, Spark Streaming, and MLlib.

Contributions to Stubby4j (Development)

https://github.com/azagniotov/stubby4j/pull/50

Added functionality to serve files from the filesystem path based on the RegEx expression specified in the request.

Contributions to the Spring Security OAuth (Development)

https://github.com/spring-projects/spring-security-oauth/commits?author=radek1st

Extended the expression methods to allow testing for existing scope by specifying a RegEx expression.

Time-locked Wallets: An Introduction to Ethereum Smart Contracts (Publication)

https://www.toptal.com/ethereum-smart-contract/time-locked-wallet-truffle-tutorial

Launch yourself into Ethereum smart contract development with the Truffle framework! In this tutorial, Toptal Freelance Ethereum Developer Radek Ostrowski shows you how to create a practical ĐApp in the Solidity language, complete with its own ERC20 token.

How I Used Apache Spark and Docker in a Hackathon to Build a Weather App (Publication)

https://www.toptal.com/spark/apache-spark-docker-hackathon-weather-app

Hackathons often inspire engineers to create amazing software. By blending various technologies together, really useful and often fun projects can be realized in a short period of time. In this article, Toptal engineer Radek Ostrowski shares his experience participating in the IBM Sparkathon, and walks us through how he elegantly combined the power of Apache Spark and Docker in IBM Bluemix to build a weather app.

Getting Started with Docker: Simplifying Devops (Publication)

https://www.toptal.com/devops/getting-started-with-docker-simplifying-devops

Docker, an open source tool, has changed the way we think about deploying applications to servers. By leveraging some amazing resource isolation features of the Linux kernel, Docker makes it possible to easily isolate server applications into containers, control resource allocation, and design simpler deployment pipelines. Moreover, Docker enables all of this without the additional overhead of full-fledged virtual machines.

Introduction to Apache Spark with Examples and Use Cases (Publication)

https://www.toptal.com/spark/introduction-to-apache-spark

In this post, Toptal engineer Radek Ostrowski introduces Apache Spark -- fast, easy-to-use, and flexible big data processing. Billed as offering "lightning fast cluster computing", the Spark technology stack incorporates a comprehensive set of capabilities, including SparkSQL, Spark Streaming, MLlib (for machine learning), and GraphX. Spark may very well be the "child prodigy of big data", rapidly gaining a dominant position in the complex world of big data processing.

Toptal Mentor

Radek is a mentor in the Toptal Global Mentor’s Program. This program is a partnership between Toptal and General Assembly to provide high quality mentorship for students from minority and low income backgrounds who are looking to begin their careers as professional software engineers. Radek shows commitment to diversity in tech by mentoring a General Assembly student every week for a year, covering everything from coding tips and tricks to advice on making it in the industry.

Languages

Scala, Java, Python, Solidity

Frameworks

Spring, Play Framework, Machine Learning, Apache Spark, Hadoop, Truffle

Libraries/APIs

Spark Streaming

Paradigms

Scrum, Agile Software Development, Kanban, Data Science, Functional Programming

Platforms

Mac OS, Linux, Docker, Blockchain, Apache Kafka, Ethereum, Amazon Web Services (AWS)

Storage

Cassandra, NoSQL, RedShift

Other

Ethereum Smart Contracts

Master of Science (with distinction) degree in High Performance Computing

2005 - 2006

University of Edinburgh - Edinburgh, UK

Bachelor of Science (with honors) degree in Computing

2004 - 2005

Edinburgh Napier University - Edinburgh, UK

Bachelor of Science degree in Physics with IT

2001 - 2004

Nicolas Copernicus University - Torun, Poland

Architect Certification for Apache Cassandra

JUNE 2017 - PRESENT

DataStax

Developer Certification for Apache Spark

MAY 2015 - PRESENT

Databricks

Java Web Services Certified Expert

JANUARY 2014 - PRESENT

Oracle