Guilherme Giannoulakis, Developer in Chiang Mai, Thailand
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Guilherme Giannoulakis

Verified Expert  in Engineering

Full-stack Developer

Chiang Mai, Thailand
Toptal Member Since
June 18, 2021

Guilherme is a full-stack developer specializing in optimized interfaces. He has worked on over 200 websites, eCommerce solutions, and web applications. He has guided and developed solutions for startups, from idea to execution, created a custom CMS for a private university with multiple access levels and dynamic features, and developed a subscription-based training platform where hundreds of users seamlessly migrated from the old platform, reducing transaction fees by 50%.


Xendit Incorporated
MongoDB, PostgreSQL, Node.js, TypeScript, APIs, React, Microservices...
React, JavaScript, Vue, Laravel, Full-stack, Databases, Linux, Git, Vercel...
Bravo Interativa
HTML5, CSS, JavaScript, Vue, Content Management Systems (CMS), WordPress...




Preferred Environment

Visual Studio Code (VS Code), Front-end, APIs, Content Management Systems (CMS), Automation

The most amazing...

...tool I've developed was a website builder for marketing agencies, making them more efficient and increasing revenue by bringing in more customers.

Work Experience

Senior Software Engineer

2021 - PRESENT
Xendit Incorporated
  • Automated manual processes by researching, planning, proposing, and implementing solutions for a payment infrastructure platform.
  • Integrated different services and created dashboards, allowing internal teams more autonomy and productivity.
  • Helped close gaps in revenue by investigating different scenarios across multiple products and business logic.
Technologies: MongoDB, PostgreSQL, Node.js, TypeScript, APIs, React, Microservices, User Interface (UI), Datadog, Databricks, Scrum, Unit Testing, Automation

IT Conusltant

2016 - 2021
  • Developed process automation with bots and API integrations, reducing the friction for new customers.
  • Optimized websites for performance and SEO, using technologies such as static site generation and edge caching.
  • Guided and developed solutions for startups, from idea to execution.
Technologies: React, JavaScript, Vue, Laravel, Full-stack, Databases, Linux, Git, Vercel, Amazon Web Services (AWS), Systems Analysis, IT Project Management, Node.js, HTML5, CSS, Content Management Systems (CMS), WordPress, PHP, Custom CMS Development, Front-end, Serverless, Express.js, Redis, Cypress, React Native, Next.js, jQuery, Puppeteer, MySQL, Firebase, APIs, Payment Gateways, Automation, TypeScript, Microservices, Web Scraping, Scraping, Docker, ECMAScript (ES6), GitHub, Python, HTML, User Interface (UI), Tailwind CSS, Data Scraping, WebSockets, AWS Lambda


2012 - 2016
Bravo Interativa
  • Developed custom software to support client acquisition and content management.
  • Developed hundreds of websites, coding detailed designs to responsive websites.
  • Started this company with a partner, surmounting many challenges as a business, dealing with a variety of clients and requests.
Technologies: HTML5, CSS, JavaScript, Vue, Content Management Systems (CMS), WordPress, Laravel, PHP, IT Project Management, Linux, Git, Systems Analysis, Full-stack, Databases, CodeIgniter, Custom CMS Development, Front-end, jQuery, MySQL, APIs, Payment Gateways, Automation, GitHub, eCommerce, HTML, User Interface (UI)

Web Developer

2011 - 2012
Falara Gestão de Marcas
  • Worked closely with designers to create great front-end experiences for marketing campaigns.
  • Improved the team's web capacity, providing in-house solutions for clients.
  • Developed a 3D product personalization tool with Blender and Python scripts.
Technologies: Content Management Systems (CMS), JavaScript, HTML5, CSS, PHP, Python, ECMAScript (ES6), eCommerce, APIs, MySQL, jQuery, PostgreSQL, Front-end, Custom CMS Development, CodeIgniter, Full-stack, Systems Analysis, Linux, HTML

Marketing Assistant

2007 - 2011
  • Developed a custom CMS solution for the main university website, with multiple access levels and dynamic features. This solution is still currently being used (2021).
  • Developed several solutions for internal needs, including integration with the main academic software.
  • Collaborated with end users, understanding their needs and providing solutions.
Technologies: PHP, CodeIgniter, Custom CMS Development, Front-end, PostgreSQL, Linux, Systems Analysis, JavaScript, Full-stack, Databases, HTML5, CSS, Content Management Systems (CMS), WordPress, jQuery, MySQL, APIs, HTML

Theme Deploy
A website builder for marketing agencies. It was created to be user-friendly yet flexible. I planned the solution from scratch, then developed and published it. To improve flexibility, I developed a custom micro-front-end architecture, allowing the source code of any block to be edited or created. A custom build process was developed to generate the final code (HTML, CSS, JavaScript) with optimized images. Serverless and edge caching were incorporated into this project to allow scaling.

Estética Experts
A subscription-based training platform for healthcare professionals. I planned and developed a new member area, offering clients a better user experience. Hundreds of users were seamlessly migrated from the old platform. I integrated it with the new payment gateway, reducing the transaction fees by 50%.

A personalized shoes brand where every product is unique. I developed the entire eCommerce solution, including product personalization and previews, a customized checkout, integration with payment gateways, delivery companies, invoicing, and marketplaces, and an ERP with product ID management, tracking the production process.

Univates CMS
Univates is a university in the south of Brazil that has graduated over 25,000 students since 1969. I joined the marketing team and created a custom CMS platform for web campaigns, including the main website. It brought several benefits for the team and the institution, such as the flexibility to create personalized designs, faster page loads, unification of different CMS solutions across websites, autonomy for other sectors to keep their content updated on the web, and easier integration with academic and other third-party software.
2006 - 2013

Bachelor's Degree in Information Systems

University of Taquari Valley (Univates) - Lajeado, Rio Grande do Sul, Brazil


Node.js, React, Vue, jQuery, Puppeteer


Git, GitHub


Laravel, Express.js, Next.js, Tailwind CSS, CodeIgniter, Cypress, React Native


Microservices, Automation, Unit Testing, Scrum


JavaScript, HTML5, CSS, PHP, HTML, ECMAScript (ES6), TypeScript, Python


MySQL, Databases, PostgreSQL, MongoDB, Redis, Datadog


Linux, Vercel, WordPress, AWS Lambda, Amazon Web Services (AWS), Firebase, Docker, Databricks


Systems Analysis, Full-stack, Content Management Systems (CMS), Custom CMS Development, Front-end, Serverless, Web Scraping, Scraping, User Interface (UI), Data Scraping, Payment Gateways, WebSockets, IT Project Management, APIs, eCommerce

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