Pantelis Vratsalis, Software Developer in Athens, Central Athens, Greece
Pantelis Vratsalis

Software Developer in Athens, Central Athens, Greece

Member since November 19, 2013
Pantelis loves coding and helping teams grow their skills. He's a polyglot engineer specializing in Java, Scala, Python, Ruby, JavaScript, PHP, and other tried and tested tools and frameworks, including React and Vue. He enjoys working with complex codebases and big data and has experience using the right tools for the job.
Pantelis is now available for hire

Portfolio

  • Glispa
    Java, Scala, Vert.x, Kafka, Hadoop, Hive, Spark, Flink, Presto, Druid...
  • Plannaro.com
    Ruby on Rails, React, PostgreSQL
  • Anyroad
    Ruby on Rails, React, PostgreSQL

Experience

Location

Athens, Central Athens, Greece

Availability

Part-time

Preferred Environment

Linux, Vim, VS Code, Git, Python, Ruby, Java

The most amazing...

...thing I've coded is a retargeting DSP for programmatic advertising. It was a great challenge due to the traffic scale (150,000 reqs/second) and complexity.

Employment

  • Senior Engineer and Tech Lead

    2017 - 2020
    Glispa
    • Worked on retargeting dynamic audience segmentation and personalized ads. Technologies used include Java, Scala, Vert.x, Kafka, Aerospike, and big data for analytics and reporting.
    • Built APIs that power UIs for reporting and campaign management purposes using Node.js and GraphQL.
    • Deployed and scheduled web applications using Docker, Nomad, Consul, and Kubernetes.
    Technologies: Java, Scala, Vert.x, Kafka, Hadoop, Hive, Spark, Flink, Presto, Druid, Kubernetes, Node.js, GraphQL
  • Tech Lead

    2016 - 2017
    Plannaro.com
    • Co-founded and led technical projects. Used technologies including Ruby on Rails for the back-end APIs, React for the front end, PostgreSQL, Redis, and Roda for the landing pages and marketing website.
    • Integrated multiple external services for things like email, SMS, geolocation (e.g., Twilio, Nexmo, Sendgrid, Mailgun).
    Technologies: Ruby on Rails, React, PostgreSQL
  • Senior Software Engineer

    2015 - 2016
    Anyroad
    • Worked with a team of six developers to build the dashboard and front pages of experience booking (tour guides, etc.).
    • Built a single-page application with React and Ruby on Rails on the back end.
    Technologies: Ruby on Rails, React, PostgreSQL
  • Full-stack Web Developer

    2014 - 2015
    SuperTasker.com
    • Owned most of the features of the website (API development and front-end AngularJS work).
    • Collaborated with a small team of three reporting directly to the CEO.
    • Contributed to the development of the back end (PHP Yii framework, MongoDB) and front end (Angular 1.4).
    Technologies: PHP, AngularJS
  • Web Developer and Team Lead

    2013 - 2014
    Freelance
    • Contracted for a Swiss online learning platform for sales people. Developed the platform in Python with the Pyramid framework.
    • Developed for a social wifi startup. Built several aspects of the application visible to visitors and the control panel for the clients (wifi network owners).
    • Led a team with Stratagem Technologies, Ltd. Technologies used include Python, Node.js, AngularJS MongoDB, and Redis. Used big data from the sports betting industry for statistical analyses and other purposes. Managed a distributed team of six developers. Built and maintained REST APIs and API consumers using Python.
    Technologies: Python, Pyramid, Pytest, ZombieJS, Selenium, AngularJS, PHP, PHPUnit
  • Web Developer

    2008 - 2012
    Freelance
    • Developed several projects as a freelancer. Created a startup company for online market research.
    • Created brochure websites for several clients using WordPress.
    • Built an online polls web application.
    Technologies: PHP, WordPress, CodeIgniter, Kohana

Experience

  • Online Market Research Project (Development)

    Currently, the website has suspended its functions. This website was online for three years (beginning 2011 till the end of 2013) for an online market research firm, but it has currently suspended its functions. It had a panel to recruit online members (around 4,000 members). I created this as a startup venture and developed both the front and back end (admin interface and user interface). I also handled marketing efforts (SEO and SEM). The web application was developed with PHP and CodeIgniter, and the data was stored using MySQL.

  • Online Polls Website (Development)

    This project enables the creation of web polls and subsequent embedding of them on a website. It is also capable of obtaining the URL/link/QR code of the poll to share it and get responses. The project was developed with PHP and the Kohana framework and uses MySQL to store data.

  • Eduno (Development)
    http://my.eduno.com

    Eduno.com is an online learning platform for salespeople based in Switzerland. It allows companies and individuals to educate themselves in sales-related subjects with online videos and interactive quizzes. It also has a recommendation engine for marketing purposes. I'm working on the development team of this ongoing project with six remote individual contractors. Development is in Python with the Pyramid framework. For storage, we used the ZODB NoSQL database.

  • Collection Feature for Freelancer Platform (Other amazing things)

    I developed the collections feature for an online platform for freelance developers, displaying curated collections of freelancer services. It includes an administrative interface where services are grouped into collections. Freelancers can request to be included in one or more collections.

  • Quovoo Quotes API (Development)

    Famous quotes API, available through Rapid API marketplace. Technologies used: Fastify (Node.js) for the back end with a PostgreSQL database.

  • AskBeat Shopify App (Development)

    AskBeat Easy Email NPS Surveys is a Shopify app for sending NPS surveys to store customers. The surveys are sent via email either manually (uploading a list of customers) or automatically every time an order is placed (integrating with Shopify's API). Technologies used include Ruby on Rails, Vue.js, and Bulma.

  • Vegetarian Keto Recipes Android App (Recipeno) (Development)

    A native Android mobile app for vegetarian keto recipes. Built with Java and communicates with an API built with Ruby on Rails for fetching data.

  • Theatrinos.gr (Development)

    Theatrinos.gr is a local theater performance search engine. Visitors can easily search among theaters and performances, using multiple criteria (e.g., genre, day of the week), to find performances that interest them.

    Technologies used: Ruby on rails 5, jQuery and vanilla JavaScript, SQLite 3, Sass, and Webpack for asset bundling.

    Integrations were made with Mailgun's API and with various affiliate APIs.

Skills

  • Languages

    Python, Ruby, Java, Scala, GraphQL, JavaScript, PHP
  • Frameworks

    Ruby on Rails (RoR), Pyramid, Laravel, Bootstrap, Mockery, Flask
  • Libraries/APIs

    React, Vue.js, Mandrill API, jQuery, Handlebars, MailChimp API, Facebook API, PayPal API
  • Tools

    Google Analytics, MailChimp, Mantis, Terminal, PhpStorm, Vim Text Editor, Git, GitHub, Amazon SQS, Capistrano
  • Paradigms

    Object-oriented Programming (OOP), Test-driven Development (TDD), Responsive Web Design (RWD), Class-based OOP, Unit Testing, SOLID Principles, REST, Agile Software Development, Scrum, Pair Programming, Inversion of Control, Design Patterns, Behavior-driven Development (BDD)
  • Platforms

    Apache Kafka, Ubuntu, Linux, Amazon Web Services (AWS)
  • Storage

    PostgreSQL, Aerospike, Druid.io, MongoDB, MySQL
  • Other

    Ajax, Math, Web Services, OAuth

Education

  • MBA degree in Business Administration
    2003 - 2003
    Rotterdam School of Management - Rotterdam, Netherlands (exchange program)
  • MBA degree in Business Administration
    2001 - 2003
    Athens University of Economics and Business - Athens, Greece
  • B.Sc. degree in Physics
    1997 - 2001
    University of Crete - Heraklion, Greece

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