Christos Paschalidis, Developer in Mexico City, Mexico
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Christos Paschalidis

Verified Expert  in Engineering

Front-end Developer

Location
Mexico City, Mexico
Toptal Member Since
October 25, 2022

Christos is a full-stack developer with more than eight years of hands-on experience. He has a strong background in various industries, especially healthcare and education. He has had clients across the EU and the US. Christos specializes in TypeScript, React, and Next.js on the front end, while on the back end, he works mainly with Node.js, Express.js, Nest.js, and Python/Django. When it comes to cloud providers, he is skilled in Azure and GCP.

Portfolio

Sesame
TypeScript 3, Next.js, React, GraphQL, Stripe, Express.js, Docker, MongoDB...
Dhis2
TypeScript 3, RxJS, React, Cypress, Docker, Open Source, TypeScript, HTML...
SPICED Academy (Freelance)
React, TypeScript 3, Recharts, Node.js, User Interface (UI)...

Experience

Availability

Part-time

Preferred Environment

React, Google Cloud Platform (GCP), Azure, Express.js, MongoDB, PostgreSQL, GraphQL, TypeScript 3, Next.js

The most amazing...

...work I've done was for America's #1 telehealth company in 2022. We all shared our expertise and built an impactful end product. (https://sesamecare.com)

Work Experience

Senior TypeScript Full-stack Engineer

2021 - 2023
Sesame
  • Implemented different front end and API-related features in TypeScript using Express.js and Next.js. Some of these features included a Twillio integration for the provider-client video communication.
  • Implemented monthly and yearly subscriptions, another feature that required full-stack experience with Typescript, Express.js, and Next.js. This included payments through Stripe and a whole checkout process.
  • Crafted and wrote technical specifications for the team while communicating deliveries and issues successfully to senior engineers and stakeholders.
  • Played a vital role in guiding junior engineers, providing support in feature delivery, and offering training on daily processes and systems.
  • Led our in-house security guild for three months, focusing on fortifying the web app's security.
  • Developed compelling user-facing features, thoughtfully A/B tested to ensure exceptional user experiences.
  • Worked on increasing the website's SEO ranking, which improved the overall visibility of the product.
  • Enabled insights into teams' performance through tools like Grafana and Prometheus.
  • Streamlined CI/CD pipelines and reduced deployment time, enabling bugs and releases to be live 40% faster.
  • Incorporated new infrastructure skillfully into the platform using Terraform and Google Cloud Platform (GCP), leveraging the latest technology to enhance performance and scalability.
Technologies: TypeScript 3, Next.js, React, GraphQL, Stripe, Express.js, Docker, MongoDB, Kubernetes, Terraform, Google Cloud Platform (GCP), Create React App, Aptible, PayPal API, Video Streaming, PayPal, JavaScript Testing, SEO Content, Contentful, E2E Testing, Open Source, CSS, Figma, TypeScript, Tailwind CSS, Jest, MERN Stack, PostgreSQL, Vercel, Full-stack, GitHub, Back-end Development, Stripe API, Payment Gateways, Single Sign-on (SSO), Google Sign-in, Server-side Rendering (SSR), React Query, React Hook Form, Amazon S3 (AWS S3), Auth0, Okta

Senior TypeScript Full-stack Engineer

2020 - 2021
Dhis2
  • Worked on different features on the platform using TypeScript, React, Express in the back end, and MongoDB. Some of these features include live chat communication between the client and the doctors using WebSockets.
  • Introduced end-to-end testing suites using Cypress for the front end. Automated tests for more than 35% of all the features.
  • Wrote technical specifications for the team, ensuring deadlines and deliveries were communicated with product owners.
  • Guided and supported junior engineers, assisting in feature delivery and offering valuable training on daily processes and systems.
  • Improved CI/CD infrastructure significantly and reduced Docker image sizes, resulting in faster and more reliable deployment times.
Technologies: TypeScript 3, RxJS, React, Cypress, Docker, Open Source, TypeScript, HTML, Storybook, Figma, CSS, A/B Testing, E2E Testing, JavaScript Testing, Create React App, Front-end, Jest, Recharts, Node.js, User Interface (UI), User Experience (UX), GitHub, CI/CD Pipelines, Amazon Web Services (AWS), HTML5, DOM, ECMAScript (ES6), MongoDB, React Redux, Material Design, Redux, Redux Toolkit, Firebase, Stripe, JavaScript, Web Development, APIs, UI Components, Design Systems, Express.js, Netlify, Slack, DevOps, Material UI, Web Usability, Web UX, Web UI, UI Development, Prisma, Back-end, HL7 FHIR Standard, Fast Healthcare Interoperability Resources (FHIR), Stripe API, PayPal API, REST APIs, Payment Gateways, Kubernetes, Terraform, Google Cloud Platform (GCP), Aptible, PayPal, SEO Content, Contentful, GraphQL, Tailwind CSS, MERN Stack, PostgreSQL, Vercel, Full-stack, Back-end Development, Single Sign-on (SSO), Google Sign-in, Server-side Rendering (SSR), React Query, React Hook Form, Amazon S3 (AWS S3), Auth0, Okta

Senior TypeScript Full-stack Engineer

2019 - 2020
SPICED Academy (Freelance)
  • Integrated Recharts into the Next.js e-learning platform, providing insightful visualizations of student performance.
  • Led the development of interactive charts, empowering educators to track student progress in real time and identify areas for improvement.
  • Coordinated the implementation of a responsive design overhaul, ensuring the e-learning platform's seamless usability across various devices, enhancing accessibility and user satisfaction.
  • Integrated cutting-edge authentication and security features into the platform, bolstering data privacy and safeguarding sensitive user information.
Technologies: React, TypeScript 3, Recharts, Node.js, User Interface (UI), User Experience (UX), GitHub, CI/CD Pipelines, HTML5, DOM, ECMAScript (ES6), React Redux, Material Design, Redux, Redux Toolkit, Firebase, Stripe, JavaScript, Web Development, APIs, UI Components, Design Systems, Express.js, Netlify, DevOps, Material UI, Web Usability, Web UX, Web UI, UI Development, Back-end, REST APIs, Python, Django, Docker, Kubernetes, Google Cloud Platform (GCP), Create React App, PayPal API, PayPal, JavaScript Testing, SEO Content, E2E Testing, GraphQL, CSS, Figma, TypeScript, Tailwind CSS, Jest, MERN Stack, PostgreSQL, Vercel, Full-stack, Back-end Development, Stripe API, Payment Gateways, Single Sign-on (SSO), Google Sign-in, Server-side Rendering (SSR), React Query, React Hook Form, Amazon S3 (AWS S3), Auth0, Okta

Full-stack Software Engineer

2018 - 2020
Vivy
  • Worked as a full-stack developer using TypeScript, React, and Next.js, with Express.js and PostgreSQL in the back end. Implemented an E2E cryptographic communication between the providers and the clients where users upload documents.
  • Used TypeScript to make open-source the in-house design system and the cryptographic libraries, which ensured visibility and improved overall public trust in the product.
  • Participated in the hiring and onboarding process of new software engineers, playing a crucial role in expanding the team.
  • Guided junior engineers, ensuring successful feature delivery and offering training on daily processes and systems.
  • Set up the infrastructure of CI/CD pipelines using Jenkins and CircleCI, streamlined development and deployment processes, and increased efficiency.
Technologies: TypeScript 3, React, Next.js, RxJS, Cypress, Open Source, TypeScript, HTML, Storybook, Figma, CSS, A/B Testing, E2E Testing, JavaScript Testing, Create React App, Front-end, Jest, Full-stack, User Interface (UI), User Experience (UX), CI/CD Pipelines, HTML5, DOM, ECMAScript (ES6), Google SEO, SEO Tools, React Redux, Material Design, Redux, Redux Toolkit, Firebase, JavaScript, Web Development, APIs, UI Components, Design Systems, Express.js, Netlify, DevOps, Material UI, Web Usability, Web UX, Web UI, UI Development, Sanity Studio, HL7 FHIR Standard, Fast Healthcare Interoperability Resources (FHIR), REST APIs, Docker, Contentful, PostgreSQL, Vercel, GitHub, Stripe, Back-end Development, Back-end, Single Sign-on (SSO), Google Sign-in, Server-side Rendering (SSR), Amazon S3 (AWS S3), Okta

Software Engineer

2016 - 2018
Employed @ Vimcar
  • Led the successful relaunch of Vimcar's website and skillfully implemented large features in collaboration with product designers, managers, and fellow engineers, delivering a compelling user-facing product.
  • Implemented search engine optimization successfully and developed a performance-focused web application using Next.js and Contentful, enhancing user experience and visibility.
  • Established the CI/CD infrastructure using Docker and Jenkins under the guidance of a development lead, streamlining development and deployment processes.
Technologies: JavaScript, JavaScript Testing, Next.js, SEO Content, Contentful, HTML, CSS, A/B Testing, Create React App, Front-end, Jest, Charts, Full-stack, User Interface (UI), User Experience (UX), CI/CD Pipelines, HTML5, DOM, ECMAScript (ES6), Google SEO, SEO Tools, React Redux, Material Design, Redux, Redux Toolkit, Web Development, APIs, UI Components, Design Systems, Express.js, Netlify, Material UI, Web UX, Web UI, REST APIs, Docker, E2E Testing, TypeScript, PostgreSQL, Vercel, GitHub, Back-end Development, Back-end, Single Sign-on (SSO), Google Sign-in

Junior Engineer

2015 - 2016
Intern @ Factor-E Analytics
  • Optimized the front-end application's performance successfully, working closely with the development lead to achieve impressive results.
  • Implemented D3.js graphs skillfully on the platform, providing managers with clear and insightful shop floor key performance indicators (KPIs).
  • Developed and enhanced the existing real-time notification system of the front-end application, ensuring seamless and timely updates for users.
Technologies: JavaScript, JavaScript Testing, HTML, CSS, Create React App, Charts, HTML5, DOM, ECMAScript (ES6), React Redux, Material Design, Redux, Web Development, APIs, UI Components, Netlify, Web UX, Web UI, REST APIs, Docker, E2E Testing, Figma, TypeScript, Jest, Vercel, GitHub, Back-end Development

Worked at America's #1 Telehealth Company

http://sesamecare.com/
As a software developer at America's #1 Telehealth Company, as ranked in 2022, I had the chance to be involved in a variety of projects.

In this role, my security background led me to lead our in-house security guild for three months, focusing on fortifying the web app's defenses and best security practices.

Effective communication with senior engineers and stakeholders fostered a collaborative environment where seamless feature development occurred with security as a priority. Colleagues commended this skill.

Working closely with junior engineers was rewarding. I provided guidance, helping them navigate technical challenges and understand ticket requirements.

As a team, we prioritized optimizing user experiences, introducing compelling features, and conducting meticulous A/B testing. This focus resulted in heightened engagement and positive feedback from users.

Noteworthy projects included:
• improving overall SEO ranking of the website.
• enabling data-driven decisions through tools like Grafana and Prometheus.
• obtaining valuable KPIs for evaluating team performance.
• streamlining CI/CD pipelines, reducing deployment time.
• incorporating new infrastructure with Terraform and GCP, bolstering performance and scalability.

Worked on Germany's #1 E2E Encrypted Health Information System

As a software engineer at Germany's #1 E2E encrypted Health Information, we delivered a secure and usable digital health platform with user security in mind.

I have been a front-end developer since the product's early days, which led me to hire and mentor new members. I was also an active contributor to the internal security team and assisted with implementing multiple features on the platform.

Worked on the world's largest health information management system

https://github.com/dhis2/capture-app
As a senior software developer at DHIS2, I have diligently crafted specifications for new projects in close collaboration with product designers and managers. Effective communication has been first in my mind, successfully communicating timelines and addressing issues with peers and stakeholders.

I take pride in guiding and supporting junior engineers, assisting in feature delivery, and offering valuable training on daily processes and systems. In this regard, a few of my contributions extend to pair programming with other engineers, engaging in detailed code reviews, and helping them navigate their role requirements.

I introduced E2E testing using Cypress, and we covered over 35% of the already introduced features. This has left developers and stakeholders with a more peaceful night's sleep.

Moreover, I have been instrumental in enhancing our CI/CD infrastructure and reducing Docker image sizes, leading to faster and more reliable deployment times. This optimization has resulted in a more efficient and robust development environment.

Migration of Existing Infrastructure From AWS to Azure Cloud

https://connect.berlin.redi-school.org/front/home
As a DevOps engineer at ReDi School, a nonprofit tech school, I took charge of vital infrastructure projects which impacted the platform's performance and scalability.

Noteworthy projects included migrating all existing infrastructure from AWS to Azure and improving performance.

I had the opportunity to lead the implementation of CI/CD pipelines for existing and greenfield projects, harnessing the power of GitHub Actions and Azure.

Lastly, we leveraged Terraform, which helped us manage the infrastructure of both back-end and front-end environments.

Relaunched Greenfield Brand Website for Vimcar

https://vimcar.de/
As part of my role at Vimcar, I had the chance to lead the implementation and relaunch of their new website branding.

I implemented a modern solution using Next.js and Contentful, which focused on the website's SEO ranking.

Product Managers' Toolbox

http://www.pm.tools
The Product Managers' Toolbox is a simple app where PMs can search for different techniques and methods they can use within their teams.

I developed this toolbox independently, implementing the web application and its continuous delivery.

Web App for a Carbon Emission Calculation Website

https://carbon-offset-opra.vercel.app/
Led the end-to-end development of a carbon emission calculator, a web application aimed at raising awareness and providing actionable insights on reducing carbon footprint. Utilized Next.js with TypeScript for a server-rendered, SEO-optimized front end. Incorporated Prismic CMS to enable a flexible, user-friendly content management experience, allowing stakeholders to update data and information on the platform effortlessly.

Leveraged Storybook for a component-driven development approach, significantly improving UI consistency and accelerating the development process. Created isolated, reusable components that enhanced the overall maintainability and scalability of the application.

Incorporated Cypress for comprehensive end-to-end testing, ensuring robustness and reliability in real-world scenarios. Automated test suites covered critical user journeys and validated the functionality of the carbon calculation algorithms, thereby boosting the application's credibility and reliability.
2010 - 2015

Master's Degree in Computer Science

Department of Computer Engineering and Informatics, University of Patras - Patras, Greece

AUGUST 2023 - PRESENT

NestJS

Udemy

Libraries/APIs

React, RxJS, Node.js, React Redux, Stripe, Stripe API, PayPal API, REST APIs, React Query, React Hook Form, Recharts

Tools

Create React App, JavaScript Testing, Figma, GitHub, Redux Toolkit, Slack, Webpack, Auth0, Terraform, Prisma

Frameworks

Next.js, Cypress, Tailwind CSS, Jest, NestJS, Redux, Express.js, Material UI, React Native, tRPC, Django

Languages

TypeScript 3, JavaScript, GraphQL, CSS, TypeScript, HTML, HTML5, ECMAScript (ES6), Python

Paradigms

E2E Testing, DevOps, HL7 FHIR Standard, Fast Healthcare Interoperability Resources (FHIR)

Platforms

Docker, Google Cloud Platform (GCP), Azure, Contentful, Vercel, Firebase, Netlify, Sanity Studio, Kubernetes, Amazon Web Services (AWS), Aptible

Storage

PostgreSQL, MongoDB, MySQL, Amazon S3 (AWS S3)

Other

A/B Testing, Open Source, Computer Science, Storybook, Front-end, Charts, Full-stack, User Interface (UI), User Experience (UX), CI/CD Pipelines, DOM, Google SEO, SEO Tools, Web Development, APIs, UI Components, Design Systems, Web Usability, Web UX, Web UI, UI Development, Back-end, Video Streaming, Payment Gateways, Single Sign-on (SSO), Google Sign-in, Server-side Rendering (SSR), Okta, SEO Content, Apollo, MERN Stack, Material Design, Back-end Development, PayPal

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