Christophe de Jonge, Developer in Noordwijk, Netherlands
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Christophe de Jonge

Verified Expert  in Engineering

WordPress Developer

Noordwijk, Netherlands
Toptal Member Since
March 9, 2022

Christophe is a developer with more than six years of experience in the web development field. He started working professionally as a freelance developer while studying physics and philosophy of science at the University of Leiden. In the meantime, he opened a small agency with a graphic designer and photographer as a partner. Most of the projects Christophe delivered were WordPress-based.


PHP, WordPress, Third-party APIs, W3 Total Cache, Full-stack, Yoast SEO...
The Atlantic Council of the United States, Inc
WordPress, WordPress Design, JavaScript, Interactive Charts, Charts...
HTML, CSS, PHP, JavaScript, WordPress, Webflow CMS,, HubSpot CRM...




Preferred Environment

MacOS, Slack, Asana

The most amazing...

...project I've worked on was for an online travel agency. I implemented the geolocation search and autocomplete features using Google's APIs.

Work Experience

Freelance WordPress Developer

2019 - PRESENT
  • Fixed the extremely slow-loading website by implementing page caching, resulting in an improved user experience.
  • Created an API connection with the subscription service that handles the shipping of their printed/physical magazine. The customers buy subscriptions through WooCommerce and are added to the CRM.
  • Provided support to the content and marketing teams.
  • Monitored the security of the website and kept everything up to date.
Technologies: PHP, WordPress, Third-party APIs, W3 Total Cache, Full-stack, Yoast SEO, Google Analytics, Child Themes, Search Engine Optimization (SEO), Google SEO, Performance Optimization

WordPress Developer

2022 - 2022
The Atlantic Council of the United States, Inc
  • Developed a map and table centered data visualization web app embedded in a WordPress page.
  • Determined the best database solution for the project.
  • Worked with a designer and research team to find solutions for visualization.
Technologies: WordPress, WordPress Design, JavaScript, Interactive Charts, Charts, JavaScript Charting, Data Visualization, Data-informed Visual Design, Svelte, React

Freelance Full-stack Web Developer

2017 - 2021
  • Set up an investigation to assess the causes of holes in visitor data collected through
  • Consolidated all the JavaScript files that tracked and formed handling into an ES6 webpack bundle and made it cross-compatible with WordPress, Unbounce, and Webflow.
  • Oversaw the transition from HubSpot to Salesforce Pardot.
  • Created a new website using Webflow CMS in collaboration with the marketing team.
  • Contributed to continuous speed and search engine optimization.
  • Managed and mentored a junior web developer to create a professionally setup website using Webflow CMS.
  • Managed and tutored a junior web developer to take over the essential JavaScript project in charge of lead generation in Salesforce and tracking via
  • Implemented UI changes, among other optimizations, with Google Optimize.
Technologies: HTML, CSS, PHP, JavaScript, WordPress, Webflow CMS,, HubSpot CRM, Salesforce Pardot Form Handlers, Webpack 5, Babel, APIs, Full-stack, Google Optimize, Google Search Console, Google Analytics, Content Management Systems (CMS), Child Themes, Search Engine Optimization (SEO), Google SEO, HubSpot, WordPress API, WordPress REST API, Performance Optimization, User Experience (UX), User Interface (UI)

Senior Full-Stack WordPress Developer

2017 - 2020
  • Moved and copied the existing website from a closed, fully managed (by a third-party agency) WordPress system to a self-managed WordPress installation, reducing monthly costs and allowing new business ideas to be implemented quickly.
  • Connected a third-party review system to display customer reviews on the site and calculate the current overall rating. Displayed it throughout the site and added Google snippets to display the rating on the Google search results page.
  • Overhauled the business' branding completely from a medical blue to a more high-end gold.
Technologies: WordPress, Third-party APIs

Freelance WordPress Developer

2017 - 2019
I am Reservations
  • Created an API connection to a 2nd hotel booking engine, which connected even more hotels to the website, increasing the number of accommodations from several hundred to more than 1,000.
  • Overhauled the search function to autocomplete geolocation-based search, immensely improving the user experience.
  • Oversaw, developed, and launched a complete English website translation with the necessary additions to the custom back office.
Technologies: Git, GitLab, PHP, JavaScript, WordPress, Third-party APIs, Gulp, APIs, Full-stack, Payment APIs, MySQL, User Experience (UX), User Interface (UI)

Full-stack WordPress Developer

2018 - 2018
Mijn Vastgoed
  • Designed the brand identity, logo, typography, and website for a revolutionary blockchain company's initial coin offering, potentially raising €1.5 million.
  • Used WooCommerce to allow the sale of Ethereum coins and integrated a blockchain monitoring API to automate the completion of orders. Sold 20% of the coins through the website in 14 days with a worth of approximately €300,000.
  • Created and maintained professional PDF documents on the company's Ethereum coin with Adobe InDesign.
  • Oversaw the launch process with over 1,000 downloads of the ICO's PDF in the first week.
  • Implemented complicated bulk discount of coins into WooCommerce cart.
Technologies: PHP, WordPress, WooCommerce, HTML, HTML5, CSS, CSS3, Photoshop CS6, InDesign CC, Adobe Illustrator, Brand Design, Typography, Web Development, Mobile Web Design, Desktop Web Design, API Integration, Responsive Layout, JavaScript, jQuery, Flatsome, Parallax Design, Ethereum, Web UX Design, WordPress Theme Design, Web Design

Full-stack Developer

2017 - 2017
Build Up Advisory Group
  • Developed and designed the main website around an existing logo.
  • Created a secondary website:, the actual nonprofit organization.
  • Sourced dozens of copyright-free and relevant images to use on the websites.
Technologies: WordPress

Full-stack WordPress Developer

2010 - 2011
Faculty Association Histartes
  • Developed a WordPress site from scratch with a custom theme and plugins.
  • Created a plugin that allowed for easy management of full-screen background advertisement (think: WeTransfer).
  • Made the content of the pages load with Asynchronous JavaScript (to keep consistency in display times of the background advertisement).
  • Helped with getting typography and brand identity to perfection.
Technologies: HTML, CSS, JavaScript, jQuery, PHP, WordPress, WordPress Themes, WordPress Plugins, Responsive Layout

Website for an Online and Printed Parenting Magazine is the website of a Dutch parenting magazine (printed and digital) with eCommerce and subscription capabilities. I extended WooCommerce with a printed magazine product type that sends subscriptions through an API directly to the company that handles the shipping of the printed magazines. I improved user experience significantly by reducing the page loading time from several seconds to a good time; before my intervention, there were times when the page wasn't even loading.

Website for Accounting SaaS (Webflow)
I was in charge of creating the Candis accounting tools (SaaS) website in Webflow CMS. I moved it from WordPress using designs from the design and marketing departments. I integrated JavaScript and performed page speed optimization to optimize the user experience.

Sales Funnel Forms and Tracking
Created a JavaScript file (JavaScript 6, Babel, webpack) that handled sales funnel form submission, visitor tracking, pop-ups, and related functionalities. The script was compatible with the WordPress site and Unbounce sales pages at the time. Eventually, it was made compatible with Webflow CMS. Standard forms could be used on all platforms. The marketing people who created the pages and inserted the forms could control the behavior via clever use of form and input data attributes.
2005 - 2011

Bachelor's Degree in Physics

University of Leiden - Leiden, Netherlands


JavaScript (Intermediate) Certificate



JavaScript (Basic) Certificate



Problem Solving (Basic) Certificate


Libraries/APIs, jQuery, WordPress API, WordPress REST API, JavaScript Charting, React, Stripe


Google Analytics, Mailchimp, Google Optimize, Slack, Asana, Adobe Illustrator, Git, GitLab, Advanced Custom Fields (ACF), Babel, Gulp, Photoshop CS6, InDesign CC, Webpack, Zapier, Figma


JavaScript, PHP, HTML, CSS, JavaScript 6, HTML5, CSS3, SQL


WordPress, WooCommerce, MacOS, Webflow CMS, HubSpot, Webflow, LAMP, Calendly, Ethereum, WordPress Theme Design

Industry Expertise

Web Design


Object-oriented Programming (OOP), Search Engine Optimization (SEO), Mobile Web Design, Desktop Web Design, Responsive Layout, Responsive Web Design (RWD), Web UX Design, Data-informed Visual Design


Divi, Svelte


MySQL, WP Engine


Salesforce Pardot Form Handlers, WordPress Plugins, WordPress Themes, Site Speed Optimization, Page Speed Optimization, Yoast SEO, Third-party APIs, W3 Total Cache, HubSpot CRM, DirectAdmin, Content Management Systems (CMS), Child Themes, APIs, Webhooks, API Integration, Full-stack, Web Security, Security, Google SEO, Web Analytics, SEO Tools, Custom Themes, Theme Customization, Performance Optimization, Webpack 5, ActiveCampaign, Brand Design, Typography, Web Development, Flatsome, Parallax Design, Unbounce, Professional Services, Payment APIs, Elementor, Google Search Console, WordPress Design, Interactive Charts, Charts, Data Visualization, User Interface (UI), SvelteKit, User Experience (UX), Membership Sites

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