Konstantinos Karachalios
Verified Expert in Engineering
Software Developer
Barcelona, Spain
Toptal member since May 8, 2017
Konstantinos is a programmer, but he doesn't just work as one—he's been coding since he was 12 on BASIC. He dropped out of a filmmaking university to return to programming. Since then, he's never stopped exploring different ways to code and for stuff to code. Konstantinos has lived around Europe and California while working on many web services, designing ETL pipelines, and leading a cross-functional team, all of which have allowed him to develop a great sense of adaptability.
Portfolio
Experience
- Linux - 10 years
- Ruby - 9 years
- Ruby on Rails (RoR) - 9 years
- Test-driven Development (TDD) - 7 years
- Agile - 6 years
- Docker - 3 years
- NixOS - 2 years
- Clojure - 1 year
Preferred Environment
Trello, Git, Linux
The most amazing...
...work I've done was to rewrite a part of a Perl monolith in Rails and deploy it with zero downtime despite the millions of requests it served each day.
Work Experience
Ruby on Rails Engineer
Benefitbay, Inc.
- Upgraded the Rails application from v3 all the way to v7 with no negative impact on the rest of the team.
- Triaged bugs and performed root-cause analysis daily to improve the web application's robustness.
- Planned multiple projects to improve our security posture.
Co-founder and Back-end Engineer
a Startup Company
- Developed a voice-first communication desktop app from scratch, using WebRTC and other web standard technologies.
- Organized and prioritized the work needed to achieve an MVP with Trello and GitHub projects.
- Architected the deployment on Linode virtual machines, emphasizing security and performance.
Freelance Senior Software Engineer
Deliveroo
- Designed a secure and performant round-trip computation of accounting corrections and adjustments between modern and legacy systems.
- Mentored a junior colleague in the mailing system of Ruby on Rails and background jobs processing and batching.
- Integrated a CI tool via its API with a code editor used by various colleagues to provide more direct visibility into the company's work progress.
Data Engineer
Scribd
- Designed and implemented two high-traffic ETL projects.
- Facilitated the upgrade, migration, and refactoring of numerous ETL pipeline jobs.
- Interviewed dozens of candidates for various teams and skillsets.
- Introduced a valuable vendor to the company, who ended up being the linchpin of the company's future technology strategy.
Staff Engineer
Solarisbank
- Designed and developed the digital banking solutions on a microservices architecture.
- Interviewed potential hires to expand the team to about double the size.
- Aided in the transformation towards Agile development.
- Promoted to staff engineer for the latter half of my job.
Senior Consultant
Tesco (via ThoughtWorks)
- Built a robust solution that integrated with many other services as part of a client onboarding flow.
- Developed and maintained a flexible deployment platform built on AWS.
- Mentored colleagues on our tech stack and web technologies in general.
Senior Software Engineer
Skyscanner
- Migrated a Rails app from Heroku to AWS.
- Took responsibility of the application's security and data privacy.
Software Engineer
- Developed a recruiting tool with the back-end code written in Ruby and Rails and the front-end code in JavaScript and Backbone and later rewrote it in CoffeeScript and Marionette.
- Migrated one of the most traffic-intensive parts of the platform to Rails and its data to a new schema with zero downtime.
Web Developer
Skroutz
- Rewrote a gaming news website from PHP to Rails.
- Developed a simple bug-tracking tool (Bugja).
- Took responsibility of the back-office application.
- Developed a simple visual programming language for the moderators to automate part of their tasks.
Experience
Racer Maker (Working Title)
https://github.com/vrinek/racermakerEducation
Specialization in Deep Learning
Deeplearning.ai | Coursera - Online
Course Certificate in Machine Learning
Stanford University | Coursera - Online
Statement of Accomplishment in Introduction to AI
Stanford University | Coursera - Onlnine
Skills
Libraries/APIs
Sidekiq, Node.js, TensorFlow, Keras, Backbone.js, jQuery, Protobuf, React, AMQP, REST APIs, WebRTC
Tools
Git, Jira, Trello, Varnish, Jenkins, CircleCI, Amazon Elastic Container Registry (ECR), AWS CloudFormation, Amazon Simple Email Service (SES), GitHub
Languages
Ruby, Scala, Python 3, Sass, JavaScript, Clojure, GraphQL
Frameworks
Ruby on Rails (RoR), Apache Spark, Sinatra, Angular, Redux, Selenium, pgTAP, Tauri
Paradigms
Microservices, REST, Scrum, Object-oriented Programming (OOP), Test-driven Development (TDD), Agile, RESTful Development, Unit Testing
Platforms
Docker, Jupyter Notebook, Databricks, MacOS, Heroku, Amazon Web Services (AWS), Apache Kafka, Linux, Linode
Storage
MySQL, Redis, Databases, PostgreSQL, Elasticsearch, Riak, Memcached, Sphinx Search Engine, Apache Hive, MongoDB, Amazon S3 (AWS S3)
Industry Expertise
Project Management
Other
Web Development, Full-stack, Software Architecture, RESTful Microservices, Minimum Viable Product (MVP), Code Review, APIs, IT Security, Deep Learning, Delta Lake, Cloud, GoCD, Machine Learning, NixOS, Integration Testing, PostGraphile, Mediasoup, Sphinx, Integration, Insurance APIs, Information Security
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