Jeroen D.

For a few small clients and my own needs I started as an hosting provider. Currently it is only hosting my own services.

When I started as a freelancer I did some of the following things, please check the rest of my profile for more current projects: - user authentication (incl. registration, etc.) and user administration for numerous clients - Software package in Visual C++ that uses the DOM to store data(-structures), and at the same time XML as the basis of a scripting language - Encryption and HTTP proxy authentication - Web-based document management system

All kinds of Internet projects using PHP as a freelancer or consultant for small/medium businesses to large corporations.

Building an simple web application to allow invoices to be registerd digitally at the Spanish Tax Office as required by 2027 (Veri*factu) for a Dutch dentist using a Dutch dentist practice management application to manage patient data and to issue invoices. After first having investigated and connecting the application to the corresponding API, I decided with the customer to choose an existing invoicing API provider as that would be much cheaper for the client. Initially started using ChatGPT and Gemini, later started to use Claude Code and claudex.

Altix is a Fintech startup based in the Netherlands that is making the Private Equity sector accessible to everybody. Started coding from scratch and within a few months we had our first onboardings, growing rapidly after. Among others I was for example responsible for: - Bootstrapping the application, both frontend and backend - Sign up and Investment flow - KYC using third-party provider - Digital signing of contracts using third-party provider - DevOps (incl. server architecture, automated deployments, deployment scripts, etc.) - Code Quality - Knowledge sharing with later added team of outsourced developers, which involved among others pair programming (XP) sessions and documenting business logic, coding standards, development/deployment process. - Securing access to the data

I was asked to do a complete inventory of a mobile e-wallet application (Android, iOS swift) including the corresponding API and control panel (CakePHP), including connectivity to third-party providers, tech stack, hosting, etc. After that I was tasked to lead the complete development of the project, for which I built a small team of developers to fix discovered issues and to prepare the application for public release. In order to do so I implemented a development process, moving the source code into a source control system (GitLab), introducing to work with branches (GitLab Flow with environment branches), adding database migrations, dotenv-based configuration, enabling the use of different environments (such as development, test, production), configuring automated deployments and adding docker configuration to be able as a new developer to quickly start with development. Furthermore, I was also responsible for deploying, maintaining and monitoring the server infrastructure in AWS using Ansible.

For a group of medical clinics I was asked to do an inventory of the PHP 5.x based legacy in-house application to manage customer data and test results, targeting specifically the security of the system as it concerned medical data. After that I updated the code for PHP 7.4, moved the source code into source control (GitLab) restructured the source code (also adding some basic unit tests, SQL and PHP-based database migrations, dotenv-based configuration and minor changes to the data model) and fixed the discovered and other minor issues (some of those issues where addressed using encryption). To prepare for automated deployment based on pushes to specific branches (GitLab Flow with environment branches) I wrote an Azure DevOps pipeline to be used for testing before deployment and configured a docker container to mimic the server used in Azure DevOps.

For a VoIP provider I wrote a small script to communicate call status to a third party provider. (PHP, MySQL, Asteriks; Linux, Mac OS X)

For two internal projects enabling automated processing of invoices and managing server infrastructure I used (among others): - Invoice2data, a python library to extract data from invoices - Ansible, an open-source software provisioning, configuration management, and application-deployment tool enabling infrastructure as code - Terraform, another open-source infrastructure as code software tool - Shell scripts The project to manage server infrastructure is currently on hold.

For a Dutch customer offering services to help companies manage and communicate with their employees, I improved their development process by moving the source code into a source control system (GitLab), introducing to work with branches and merging (GitLab Flow with environment branches), adding database migrations, configuring a test environment, configuring docker container to quickly have a fully working development environment, configuring automated deployments (GitLab pipelines) and educating other developers and project managers on how to use these. Furthermore, I also fixed bugs and implemented new features. (PHP, MySQL; Docker, GitLab, git; Linux, Mac OS X)

For a online sneakers reselling platform I did the following: - Preparing integration with DHL Express for EU-wide shipping - Preparing for redesign API using OpenAPI 3.0 - Minor bugfixes and functionalities (PHP, MySQL, Laravel; GitHub, Postman, Trello; Linux, Mac OS X)

For a classified car classics website built using Laravel, I have fixed many layout and functionality issues.

I was able to help Iristrace with some advanced software engineering issues such as security and reporting.

Working as a team member on a huge project written in CodeIgniter (100k+ LOC) mostly resolving security vulnerabilities in an automated fashion using regular expressions in a Makefile.

For an automotive company I was asked to perform some minor bugfixes and other maintenance on their API and semi-internal website (made with CakePHP) and app (created with Appcelerator Titanium).

For this client I fixed some minor issues in a web application after they upgraded PHP.

For a online sneakers reselling platform I did the following: - Added shipping provider integration for DHL Express, allowing it to co-exist with the previous shipping provider (MyParcel) integration - Added migrations, tests - Many minor functionalities and improvements, among others in automated deploys and translation processing

Through my Alicante Tech Meetup I was contacted by Kuveno to help them find developers in the Alicante area to work remotely on their platform. Pretty quickly I found two Javascripts developers which became my employees working exclusively for Kuveno.

I saw an opportunity working for Dutch clients with a team in Alicante, Spain. So I opened an office and hired some programmers. Unfortunately, it was more difficult than I expected and after 2 years I had to close the office.

Because of interest and trying a possible business idea I created an Alexa skill that allows a user to order wine. The products contained in the database where extracted from the provider's website using scraping.

Together with some locals, including some of my employees, we worked as a bootstrapped startup on a mobile application that communicates with an API built with Laravel. Initially I was only responsible for the web part (API + admin), but since I have started to build the mobile application from scratch using flutter.

A house rental intermediary website wanted to migrate from NodeJS to Laravel, so with a small team we built everything from the ground up based on a provided new design. This involved, among others, regularly retrieving rentals information from different API's, displaying rentals on map, allowing the rentals to be administered, sending emails using Elastic Email, etc.

For a startup for large battery monitoring I built an API with administration area to receive measurements at 5-minute intervals for up to tens of thousands of battery monitor devices in order to trigger alerts for required maintenance. The API protocol was consisely described so that the hardware developer could implement it accordingly on the Arduino platform. The server architecture was setup using Aurora DB Cluster for production and Percona XtraDB Cluster for test, on top of a tinc VPN with HAProxy proxying both the web and database services in order to allow easy maintenance additionally using reverse proxy CloudFlare.

An academic researcher wanted to have an application to make high school students' homework more efficient by having an application that allows students to do exercises online and to have statistics available for analysis.

Using Python to build the management platform for Stackscale. Some of the projects I initiated or worked on: I worked on the following projects: - Authentication and authorisation API using the latest encryption standards - Queue library for executing tasks including Python modules, external scripts and repeating tasks - Different tools and modules for management of VMware environments - Drivers to control advanced netwerk equipment like switches and routers (Cisco / Force10 / Arista) - Management of network attached storage (NAS) equipment and datastores (volumes) (NetApp / Nexenta / Oracle / Solaris / ZFS) - Add new functionality to an API written in Django REST Framework with an accompanying user interface built with ExtJS

Built a couple of Magento websites, (e.g. http://www.brunoklassiekpresenteert.nl), now working on 2 private projects being built as extension on Magento (incl. PHPlist extension). Furthermore, helped some customers with fixing issues and adding functionality in existing Magento webshops.

Part-time I'm helping with maintenance of their Magento platforms.

The Magento project that I would work on was cancelled after a couple of days after which I made myself useful for more than a week as frontend developer for monumenten.nl and NS Hispeed (PHP, MySQL, Zend Framework, jQuery, HTML5, CSS3; Linux, Mac OS X, Windows).

At Dialogues Technology, a innovative company which uses mostly Java to develop solutions for their clients, I have been asked to demonstrate what PHP can do for them and their clients in terms of speed, ease of programming and use of existing frameworks. The project I worked for was ABN AMRO Smartjobs, an internal HR temporary placement project.

As a PHP software developer I again worked on implementing new functionalities into the website and related maintaince work (PHP, Smarty, MySQL, JavaScript; Linux, Windows).

For this specialised classical CD and DVD store setup a webshop for selling tickets to classical concerts based on Magento with custom bugfixes and custimisations (PHP, MySQL, Magento; MacOSX, Linux, Windows).

For this customer I setup a B2B webshop based on Magento with custom bugfixes and custimisations (PHP, MySQL, Magento; MacOSX, Linux, Windows).

Voor deze website heb ik een aantal bugs opgelost en nieuwe functionaliteiten geïmplementeerd (PHP, Zend Framework, MySQL; MacOSX, Linux, Windows).

As a PHP software developer I will be implementing new functionalities into the website and related maintaince work (PHP, Smarty, MySQL, JavaScript; Linux, Windows).

As a PHP software developer I contribue to the development team responsible for the TomTom website. Some of the projects I have done: Apache module for authentication based on mod_auth_tkt (C, OpenSSL, FreeTDS; Linux) Improving the application framework (PHP, Smarty, MSSQL, JavaScript; Linux, Windows)

For their website I have designed and built user registration and authentication, handling MMS messages to be viewed from the web and lots of other web based applications (PHP/PEAR, LDAP, MySQL, HTML, JavaScript, Java, Perl; Linux, Windows)

Using PHP to import and process data (photos, images, spreadsheets, documents) into an MySQL database. This database was then exported to an SQLite database to be used from an application CD. (PHP, MySQL, SQLite, VC++ 6, STL; Linux, Windows)

Together with another programmer we built the personal stamps (Persoonlijke Postzegels) web application, which is currently still in use.

As a Programmer Analyst (Senior since January 2001) I have been responsible for the design and development of the frontend part for the regedoc system, which is a system for sending and receiving documents registered and secured over the Internet or intranet. This encompassed the design and implementation of an ISAPI for Microsoft IIS, using performance counters, registry settings, the eventlog, encrypted communication and timestamping of documents, and an additional configuration utility. To do this I used MFC, PGP, Sybase and Oracle backend database (Rogue Wave DBTools++, Oracle OO4O, ODBC). Furthermore, I also dealt with business security as a member of the Security Project Team and helped getting the BS7799 certification.

As a programmer I worked on: - guardian system for machines, websites, database, payment systems et cetera (C, shell scripts; IRIX) - porting of diverse Perl scripts to PHP (PHP; Windows NT, IRIX) - system for preventing abuse of website account/authorisation by multiple persons (C, NSAPI, msql, shell scripts; IRIX) - diverse programs and scripts for websites, authorisation- and payment databases (C, PHP, msql, shell scripts; IRIX, Linux) - shops for websites (products, shopping basket and interface to paymeny module) (PHP, msql; IRIX) - porting of (Unix) C JPEG6a library to VC++ for an ActiveX control (Visual C++ 5.0; Windows 95) - porting of the C++ FraunHofer MPEG1-III audio decoder to Java (C++, JDK 1.1; Windows 95, IRIX) - Adobe Premiere Plugin for JPEG and AVL (LiveStream) (Visual C++ 5.0; Windows NT)

As a Student Assistant for the courses Software Engineering and Computer Networks with the faculty of Mathematics & Computer Science I coached students with their pratical work for these courses. During the first course I coached five groups of about five persons. They had to implement a 'large' program as a team effort. In this case the program to implement was a route planner. The distinguished stages were: requirements specification, design, implementation (in C++) and evaluation. I also was responsible for judging the submitted results. During the second course I coached groups of one or two persons with the design and implementation (in C) of (a simplification) of the IP and UDP network protocols, and an tftp daemon and client. I was only responsible for coaching the groups.