
Pantelis Vratsalis
Verified Expert in Engineering
FastAPI Developer
Pantelis is a full-stack engineer with experience building complex products using a wide array of technologies (Python, Ruby, JavaScript, Java, Go) and tools (Flask, FastAPI, Vert.x, React, Vue, Ruby on Rails, and SQL and NoSQL databases). Apart from coding, Pantelis has worked as a team lead and engineering manager in the last few years—building, growing, and managing teams and individual contributors. His work includes hiring, performance management, mentoring, and overseeing team projects.
Portfolio
Experience
Availability
Preferred Environment
Ruby, Python, Git, Linux, Kubernetes, React, Vue, Aerospike, PostgreSQL, MySQL
The most amazing...
...thing I've coded is a retargeting DSP for programmatic advertising. It was a great challenge due to the complexity and traffic scale (150,000 reqs/second).
Work Experience
Senior Software Engineer and Team Lead
Hotjar
- Bootstrapped a new team and set the direction (North Star) for the company's security and authentication/authorization.
- Built microservices for authentication and authorization (as a platform team) to enable other services to be extracted from the monolith.
- Set up security best practices and automated tests in SDLC.
Engineering Lead
Mattermost
- Led a platform (web/desktop) team and created systems to gather customers' and internal stakeholders' requirements in a structured way, focusing on the highest impact work at any given point.
- Oversaw the professional growth of all team members. Led several engineers to promotion through personal goal setting and coaching in a short period.
- Migrated our codebase from JavaScript to TypeScript.
Tech Lead
AskBeat
- Co-founded and tech-led AskBea, a Shopify partner that builds apps to help store owners grow their sales and better manage their stores.
- Handled the first Shopify app, a post-purchase and abandoned cart NPS survey scheduling and reporting software.
- Used machine learning to build the recommendation algorithm for the second app, a product recommendation engine.
Senior Engineer and Tech Lead
Glispa
- Worked on retargeting dynamic audience segmentation and personalized ads using 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.
Tech Lead
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).
Senior Software Engineer
Anyroad
- Worked with a team of six developers to build the dashboard and front pages of booking experience (tour guides and more).
- Built a single-page application with React and Ruby on Rails on the back end.
Full-stack Web Developer
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).
Web Developer and Team Lead
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.
Experience
Online Market Research Project
Online Polls Website
Eduno
http://my.eduno.comCollection Feature for Freelancer Platform
Quovoo Quotes API
AskBeat Shopify App
Vegetarian Keto Recipes Android App (Recipeno)
Theatrinos.gr
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, GraphQL, JavaScript, Go
Frameworks
Ruby on Rails (RoR), Flask, Vert.x
Libraries/APIs
React, Vue, Node.js
Paradigms
Test-driven Development (TDD), Unit Testing, REST
Platforms
Linux, Apache Kafka, Kubernetes
Storage
PostgreSQL, Aerospike, MySQL, Druid.io, MongoDB
Tools
Pytest, RabbitMQ
Other
Physics, FastAPI, Prometheus
Education
Master’s Degree (Exchange Program) in Business Administration (MBA)
Rotterdam School of Management - Rotterdam, Netherlands
Master's Degree in Business Administration (MBA)
Athens University of Economics and Business - Athens, Greece
Bachelor of Science Degree in Physics
University of Crete - Heraklion, Greece