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Christos Paschalidis
Verified Expert in Engineering
Front-end Developer
Bristol, United Kingdom
Toptal member since October 25, 2022
Bio
Christos is a full-stack developer with 10+ 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 Rust and Go on the back end and excels at using TypeScript, React, and Next.js on the front end. When it comes to cloud providers, he is skilled in Azure and GCP.
Portfolio
Aury
Expo, React Native, SQL, PostgreSQL, Fractional CTO, Performance Optimization
Ever Cars Co.
React, Go, AWS Command Line Interface (CLI), Next.js, NextAuth.js, PostgreSQL...
Hirespace
React, TypeScript 3, User Interface (UI), CI/CD Pipelines, HTML5...
Experience
- Next.js - 8 years
- React - 8 years
- Node.js - 7 years
- TypeScript 3 - 5 years
- TypeScript - 5 years
- Docker - 4 years
- Kubernetes Operators - 3 years
- Rust - 2 years
Preferred Environment
Google Cloud Platform (GCP), Azure, PostgreSQL, TypeScript 3, Next.js, Rust, Go, Amazon DynamoDB
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
Fractional CTO
2025 - 2025
Aury
- Led greenfield React Native development by architecting and building the mobile application from the ground up, establishing technical foundations and development practices for a scalable conversational AI platform.
- Designed scalable back-end infrastructure and implemented robust API architecture and database design to support real-time conversational AI features with sub-second response times and multi-user concurrent sessions.
- Built a conversational AI integration layer, designing and implementing LLM integration architecture with proper error handling, fallback mechanisms, and conversation state management for a seamless user experience.
- Established technical strategy and roadmap, defining long-term technical vision, technology stack decisions, and development milestones to guide product evolution and team scaling.
Technologies: Expo, React Native, SQL, PostgreSQL, Fractional CTO, Performance Optimization
Founding Full-stack Engineer
2024 - 2025
Ever Cars Co.
- Led full-stack projects by directing project refinement and task distribution across the team, ensuring alignment with product goals.
- Managed the project backlog by writing my own ticket workflows, crafting clear and actionable tickets to enable efficient development and accountability.
- Owned the end-to-end development of multiple projects, such as the checkout flow, by leading from initial customer problem analysis and competitive research to technical specification and implementation (designs handled by a designer).
Technologies: React, Go, AWS Command Line Interface (CLI), Next.js, NextAuth.js, PostgreSQL, Artificial Intelligence (AI), RESTFul APIs, API Integration, AWS Lambda, Serverless, SQL, n8n, OpenAI, Content Management Systems (CMS), Large Language Models (LLMs), Architecture, LangChain, Supabase, Redis, Design, Web UI Design, UI Design, Cloud, Git, Google Analytics, Google Analytics API, Sentry, WebSockets, Amazon Web Services (AWS), Google Cloud, Analytics, Headless CMS, Multitenancy, Sitemaps, CRM APIs, Chatbots, OpenAI API, Conversational AI, LangGraph, Pinecone, AI Pipeline, Performance Optimization
Founding Full-stack Engineer
2021 - 2023
Hirespace
- Navigated technical and product ambiguity to establish the foundational architecture, ensuring long-term maintainability.
- Managed the project backlog by crafting clear, actionable tickets for myself and the team.
- Researched and implemented the full payment flow with Stripe, focusing on creating a clear and user-friendly experience for the marketplace product.
- Managed cross-functional coordination between back-end and front-end teams to collaborate with product owners for feature delivery.
Technologies: React, TypeScript 3, User Interface (UI), CI/CD Pipelines, HTML5, 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, Next.js, A/B Testing, Artificial Intelligence (AI), RESTFul APIs, Speech-to-Text (STT), Speech Recognition, API Integration, AWS Lambda, Serverless, SQL, n8n, OpenAI, Content Management Systems (CMS), Large Language Models (LLMs), Architecture, Qdrant, LangChain, Supabase, Redis, Design, Web UI Design, UI Design, Cloud, Git, Google Analytics, Google Analytics API, Google Maps API, Sentry, WebSockets, Amazon Web Services (AWS), Google Cloud, Analytics, Headless CMS, Multitenancy, Sitemaps, CRM APIs, Chatbots, OpenAI API, Conversational AI, LangGraph, Pinecone, AI Pipeline, Performance Optimization
Platform Engineer
2016 - 2021
Sesame
- Led platform projects, authoring technical specifications to translate product needs into successful delivery.
- Strengthened web app security by leading the in-house security guild for 3 months, implementing critical safeguards.
- Optimized CI/CD pipelines, creating leverage via 40% faster deployments for quicker value delivery.
- Enhanced performance monitoring by implementing tools such as Grafana and Prometheus, driving data-informed decisions.
- Improved infrastructure scalability and reliability using Terraform and GCP.
- Boosted user acquisition and engagement through technical SEO improvements.
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, API Integration, Serverless, SQL, OpenAI, Content Management Systems (CMS), Supabase, Design, Web UI Design, UI Design, Cloud, Git, Google Analytics, Google Analytics API, Google Maps, Google Maps API, Sentry, Twilio, Amazon Web Services (AWS), Google Cloud, Analytics, Headless CMS, Sitemaps, CRM APIs
Software Developer
2018 - 2019
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.
- Mentored and supported junior engineers in feature development, improving delivery efficiency and fostering a knowledgeable team through hands-on training.
- Enhanced quality assurance by implementing end-to-end testing, which directly reduced production bugs impacting customer workflows.
- Guided and supported junior engineers, assisting in feature delivery and offering valuable training on daily processes and systems.
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, API Integration, Design, Web UI Design, UI Design, Cloud, Git, Google Analytics, Google Analytics API, Google Maps, Sentry, Analytics, Sitemaps
Software Engineer
2016 - 2018
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.
- Boosted productivity by streamlining onboarding and mentoring junior engineers, enabling faster ramp-up and consistent delivery.
- Contributed to knowledge sharing by open-sourcing cryptographic libraries and design systems, enhancing transparency, trust, and product credibility.
- 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, API Integration, Design, Web UI Design, UI Design, Git, Sitemaps
Front-end Engineer
2014 - 2016
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, Git
Junior Front-end Engineer
2013 - 2014
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, Git
Experience
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.
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.
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.
Migration of Existing Infrastructure From AWS to Azure Cloud
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.
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.
I implemented a modern solution using Next.js and Contentful, which focused on the website's SEO ranking.
Product Managers' Toolbox
http://www.pm.toolsThe 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.
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.
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.
Education
2010 - 2015
Master's Degree in Computer Science
Department of Computer Engineering and Informatics, University of Patras - Patras, Greece
Certifications
AUGUST 2023 - PRESENT
NestJS
Udemy
Skills
Libraries/APIs
React, RxJS, Node.js, React Redux, Stripe, Stripe API, PayPal API, REST APIs, React Query, React Hook Form, Google Analytics API, Google Maps, Google Maps API, OpenAI API, Recharts
Tools
Create React App, JavaScript Testing, Figma, GitHub, Redux Toolkit, Slack, Webpack, Auth0, n8n, Git, Google Analytics, Sentry, Terraform, Prisma, Kubernetes Operators, AWS Command Line Interface (CLI), Expo
Languages
TypeScript 3, JavaScript, GraphQL, CSS, TypeScript, HTML, HTML5, ECMAScript (ES6), SQL, Python, Rust, Go
Frameworks
Next.js, Cypress, Tailwind CSS, Jest, NestJS, Redux, Express.js, Material UI, LangGraph, React Native, tRPC, Django
Paradigms
E2E Testing, DevOps, Web UI Design, UI Design, HL7 FHIR Standard, Fast Healthcare Interoperability Resources (FHIR)
Platforms
Docker, Google Cloud Platform (GCP), Azure, Contentful, Vercel, Firebase, Netlify, Sanity Studio, AWS Lambda, Kubernetes, Amazon Web Services (AWS), Aptible, Twilio
Storage
PostgreSQL, MongoDB, MySQL, Amazon S3 (AWS S3), Redis, Google Cloud, Amazon DynamoDB
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, Artificial Intelligence (AI), RESTFul APIs, Speech-to-Text (STT), Speech Recognition, API Integration, Serverless, OpenAI, Content Management Systems (CMS), Large Language Models (LLMs), Architecture, Supabase, Design, Cloud, WebSockets, Analytics, Headless CMS, Sitemaps, CRM APIs, Chatbots, Conversational AI, Pinecone, Fractional CTO, Performance Optimization, SEO Content, Apollo, MERN Stack, Material Design, Back-end Development, Qdrant, LangChain, Multitenancy, AI Pipeline, PayPal, Telehealth, NextAuth.js
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