Serafeim Papastefanos, Developer in Athens, Central Athens, Greece
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Serafeim Papastefanos

Verified Expert  in Engineering

Full-stack Developer

Athens, Central Athens, Greece
Toptal Member Since
July 27, 2020

Serafeim is a software engineer with over a decade of professional experience and a Ph.D. in electrical and computer engineering. Serafeim is systematic and methodical with a lot of enthusiasm (and patience) when solving interesting, complex problems. His areas of expertise are with C, Java, Python, JavaScript, and a variety of frameworks (Django), libraries (jQuery), and platforms (Android, Linux RHEL/CentOS).


Hellenic Coast Guard
JavaScript, Django, Python, Spring, Java, HTML, SQL, Elixir, Phoenix, Linux...
Wagtail CMS, Django, Python, Android, Java, Architecture, Web Scraping, jQuery...
University of Washington - Main
Python, Django, JavaScript, jQuery, HTML, CSS, RHEL, Apache Solr, PostgreSQL...




Preferred Environment

Slack, Vim Text Editor, Visual Studio Code (VS Code), Linux, Windows

The most amazing...

...thing I've implemented was for my Ph.D. which was a complete system (algorithms and implementation) for fast direct video indexing and searching.

Work Experience

Senior Full-stack Developer

2011 - PRESENT
Hellenic Coast Guard
  • Introduced Django to the organization and implemented many internal apps for various needs of the organization's users, including warehouse, ship, and vehicle management.
  • Implemented the Greek Ministry of Shipping web portal, a parent organization of the coast guard called I used Wagtail, Django, and Python.
  • Developed a complete application to manage boat-driver licensing for Greece, both public-facing and back-end implementation. The public site is
  • Architected a complete application that allows the candidate students for the Merchant Marine Academies to submit their applications electronically. Created the full back end for managing these applications. The public site is
  • Implemented a complete solution for passenger ship companies to submit their ship's passenger data in compliance with EU laws. The public site is
  • Supported various legacy systems of the organization.
  • Implemented the Hellenic Coastguard web portal using Wagtail, Django, and Python.
  • Implemented a complex CRUD internal application using Elixir and Phoenix. The app supports multiple departments, each with different users properly authorized.
  • Implemented a Phoenix Liveview app for real-time exams of lifeguard candidates. People login with their profiles and see random questions. They answer in real-time, and after the time limit expires, they see if they have passed the exams.
Technologies: JavaScript, Django, Python, Spring, Java, HTML, SQL, Elixir, Phoenix, Linux, Linux RHEL/CentOS, Debian Linux, Ubuntu Server, PostgreSQL, MySQL, Architecture, APIs, Back-end, React, REST APIs, SOAP, Tailwind CSS, REST

Software Engineer

2010 - PRESENT
  • Developed the back end and most of the front end of an application with children's activities in Athens,
  • Developed the back end for a reverse-classifieds app. (
  • Developed an Android app for displaying vehicle positions on a map; a fleet management company used it to display each client's fleet.
  • Initiated the development of an Android app for fleet management. The Google Play URL is
Technologies: Wagtail CMS, Django, Python, Android, Java, Architecture, Web Scraping, jQuery, React, RHEL, PostgreSQL, APIs, Back-end, REST APIs, REST

Full-stack Developer

2022 - 2022
University of Washington - Main
  • Upgraded the project to the latest version of Python and Django. Changed all dependencies to their latest versions and used alternatives for unsupported packages. Fixed problems that were introduced because of the upgrade.
  • Changed the hosting server of from Centos to Almalinux (RHEL compatible). Upgraded all the components of, like the Apache Solr that was used for searching to the latest version and PostgreSQL.
  • Implemented some small improvements to the Liver Atlas functionality. These features were implemented in Python and Django, as well as JavaScript and jQuery.
Technologies: Python, Django, JavaScript, jQuery, HTML, CSS, RHEL, Apache Solr, PostgreSQL, Back-end

Full-stack Developer

2021 - 2022
Decent Studios
  • Created a (prototype) real-time multiplayer game using Phoenix Live View. The players were moving in a maze and could do various actions depending on where they stood to extract resources from the maze. Any number of players could join.
  • Developed a prototype real-time single-player game using Phoenix Live View. The player displays a list of choices, and based on each choice, he could change the state of the world. This was a text-only game.
  • Implemented a Phoenix LiveView app for auto-generating complex images by combining some parts. Designers could design their images, save them, etc.
Technologies: Elixir, Phoenix, Phoenix LiveView, SQL, Tailwind CSS,

Appian Software Enginner

2009 - 2011
Exus | Piraeus Bank
  • Worked in a team that installed and configured Appian BPMS in production in Piraeus bank using JBoss for deployment; was also responsible for Appian and JBoss server's health.
  • Implemented a number of complex BPM workflows in Appian. Among them were the basic user synchronization workflow between Appian and the bank's HR system and a state-inducted loan origination process.
  • Wrote a number of smart nodes (add-ons) for Appian to integrate with the bank's web services, e.g., integrations with the CRS system, the DMS, the reporting tools, and so on.
Technologies: Java, Appian, JavaScript, Administration, IBM Db2, JBoss, WebSphere, SOAP

Little City Spots

Little City Spots is a Django web app for managing children's activities in Athens. The people offering the activities can add them, and the users can search for which ones are relevant to them using different parameters, like location, date, time, age of the child, price, and so on, to decide where their child will go.

I developed this project's back end and some things from the front-end.


AskPrice is a Django project for users who are looking for skilled technicians. The user enters their job listing (i.e., my wall needs painting), and the application notifies the professionals so they could submit a proposal for fixing it.

I implemented the whole back end along with all the server administration work needed to run the app in production. The project isn't active anymore, but I have uploaded it to Heroku to offer a demo.

Boat Driver Permission System
This is the central system of boat driver permissions in Greece. People that require boat driver permission will need to submit an application to this system (either electronically or through their local port authority). Beyond the application management, the system supports creating exam issues for the boat driver candidates and printing their boat driver licenses.

I handled all the development for this web application using Django.

Everygate Tracker

This is an Android software application that tracks your vehicle's movement and sends its position to a central server. A Greek fleet management provider uses it to offer software tracking beyond hardware trackers. The application also supports integration with various Bluetooth accessories, e.g., temperature sensors, OBD data readers, and so on, to transmit even their data to the central server.

This is a Django application that can be used to save and record the food you eat throughout the day. Each user of the app adds his list of ingredients and foods and then adds what he eats during the day. The app uses a PostgreSQL database and is hosted on
2005 - 2010

Ph.D. in Electrical and Computer Engineering

National Technical University Of Athens - Athens, Greece

2000 - 2005

Master's Degree in Electrical and Computer Engineering

National Technical University Of Athens - Athens, Greece


jQuery, REST APIs, React, FFmpeg


Vim Text Editor, Slack, Apache Solr, Servlet


Django, Spring, Phoenix, Tailwind CSS, Bootstrap




Python, Java, C, Elixir, JavaScript, HTML, SQL, PHP, CSS, C#, C++, Ada, Lisp, XML, Fortran, Prolog, Pascal, Python 3


Android, Linux RHEL/CentOS, Appian, Windows, Linux, Debian Linux, JBoss, WebSphere, Visual Studio Code (VS Code)


PostgreSQL, MySQL, IBM Db2


Architecture, Web Scraping, APIs, Back-end, SOAP, Phoenix LiveView,, Wagtail CMS, Ubuntu Server, RHEL, Software Engineering, MPEG, Videos, H264, Web Servers, Algebra, Calculus, Differential Privacy, Complex Networks, Networking, Administration

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