David Marín, Software Developer in Cobeña, Spain
David Marín

Software Developer in Cobeña, Spain

Member since July 2, 2015
David is an open-source and open data enthusiast with more than 20 years of experience as a professional developer. He has acquired a broad variety of skills, including web programming (PHP and JavaScript), C, C++ (under Linux and Windows), and systems management. Of these skills, David specializes in web programming and has full-stack experience with Symfony PHP-based back ends, jQuery front ends, and WordPress-based sites.
David is now available for hire




Cobeña, Spain



Preferred Environment

JavaScript, Linux, Symfony, LAMP, PHP, WooCommerce, WordPress

The most amazing...

...algorithm I've developed is the control system for the automatic ventilation in Madrid Calle-30, a network of more than 40km of urban tunnels.


  • Web Lead Developer

    2016 - PRESENT
    The Healthy Mummy
    • Developed multiple custom features for the company website based on WordPress and WooCommerce.
    • Cleaned and optimized legacy source code to adapt it to the usage of good practices.
    • Developed multiple patches and improvements for several existing WordPress and WooCommerce plugins.
    • Implemented an automated test suite with Selenium to track the working conditions of the site.
    • Debugged and supported a variety of hosting problems.
    • Led a team of three developers working on the site front and back ends.
    • Contributed to VWO tests to improve site conversions.
    • Made needed adaptations to migrate the sites from PHP 5 to PHP 7.
    Technologies: JavaScript, WordPress Plugins, Web Hosting & Domain Setup, Docker, Selenium, MySQL, PHP, WooCommerce Subscriptions 2, WordPress, WooCommerce
  • Pro-bono System Manager | Web Developer

    2003 - PRESENT
    Fundación MAIOR
    • Managed a network of five Windows computers and a Linux file and mail server remotely.
    • Developed and deployed www.maior.es using WordPress and WooCommerce.
    • Developed and deployed www.amaysirve.es, using WordPress, and developing a template from scratch using Twig and Timber plugin.
    Technologies: WordPress Plugins, Web Hosting & Domain Setup, WooCommerce, Debian, PHP, WordPress
  • Web Developer and System Administrator

    2015 - 2020
    Navigate Oceania (via Toptal)
    • Fixed problems in a multi-domain site where the content should be replicated on all the sites.
    • Fixed a hacked WordPress installation and improved the site security.
    • Added space for advertisements on all the site pages.
    • Fixed problems with the translation plugin on the site.
    • Updated and cleaned up the plugins used on the site, as many of them weren't needed.
    • Migrated several sites from PHP 5 to PHP 7 and made the needed adaptations.
    Technologies: WooCommerce, JavaScript, WordPress Plugins, Web Hosting & Domain Setup, PHP, WordPress
  • Web Developer

    2016 - 2016
    Adapt Marketing (via Toptal)
    • Corrected several problems using WordPress API due to an attack on the server.
    • Set up a web page using WordPress and WooCommerce, including selecting and adding plugins and generating custom plugins for specific features.
    • Migrated Photoshop designs to HTML/CSS using a newly developed WordPress theme.
    Technologies: WordPress Plugins, Web Hosting & Domain Setup, Linux, WooCommerce, WordPress
  • Web Developer

    2016 - 2016
    Meridix Creative, Inc. (via Toptal)
    • Modified a website so it now uses Stripe payment gateway instead of PayPal's Payflow API.
    • Modified the style of several pages on the website.
    Technologies: JavaScript, Web Hosting & Domain Setup, Stripe, Microsoft SQL Server, Azure, PHP
  • Web Developer

    2015 - 2016
    Forelock (via Toptal)
    • Adapted the site to use Braintree payment gateway.
    • Worked on security clean-up for the whole site, removing several security issues as potential SQL injection points.
    • Developed new features involving back-end and front-end modifications.
    Technologies: JavaScript, Web Hosting & Domain Setup, HTML, MySQL, PHP
  • Software Developer & System Manager

    2006 - 2016
    • Led a team of four to develop and deploy a proprietary reporting system for Canal de Isabel II, Madrid's public drinking water supplier.
    • Managed a three-person team to develop and deploy SICE Nautilus, a web-based operational assistance system that includes incident support as well as fleet, inventory, and maintenance management.
    • Optimized queries and made back-end improvements for a web-based report system for SICE's ITS solution. Improvements allowed the generation and exporting of reports involving huge quantities of data to PDF or Excel.
    • Worked on the water control system for the Segura Basin. Dealt with the analysis, design, and implementation of new features for the Basin Control Center including interfacing with an automatic telephone service. The project was done using C++, InfoPlus.21, SCADA, and an Oracle database.
    • Worked on the analysis, design, and implementation of a new automatic calculation system (using Java and ANTLR tool) and other Java modules for the back-end of a new SCADA system for dam auscultation against a MySQL database. Deployed as the water control system for the Ebro Basin and in dams managed by Iberdrola (Spain).
    • Developed new features for the Basin Control Center (C++ services on Windows) of the River Tagus Basin. I oversaw the deployment of a new communication system and network of more than 200 embedded x86-based remote units based on Linux as well as the implementation of systems for remote administration and update capabilities for these remote units.
    • Developed automatic ventilation algorithms (PHP and proprietary languages) for the tunnel control system of Madrid Calle-30. I configured, deployed, optimized, and troubleshot ERU systems, with a special focus on ventilation and fire detection subsystems. I also developed several features aimed at improving the scalability and robustness of the remote control unit so that it could support a larger number of I/O signals and connections (C++ for embedded Linux system using x86 arch).
    • Deplyed and managed of internal Linux and Windows servers (CVS, SVN, Git).
    Technologies: ANTLR, SCADA, Highcharts, DataTables, NHibernate, ASP.NET MVC, Git, Subversion (SVN), CVS, Linux, Infoplus WMS, Microsoft SQL Server, MySQL, Oracle, PostgreSQL, Java, C++, C, LeafletJS, jQuery, Symfony, JavaScript, PHP
  • Web Developer and Technical Consultant

    2010 - 2012
    Miguel Buckenmeyer & Co.
    • Created, installed, and managed WordPress sites.
    • Integrated a web-based file manager in a PHP custom site and helped to solve problems in it due to the usage of Java-based plugins.
    • Provided technical assistance for the projects.
    • Customized an advanced WordPress template, implementing a grid design for the articles.
    • Tweaked a PHP-based website for a Spanish perfume company, solving some problems and programming some new features.
    Technologies: WooCommerce, Web Hosting & Domain Setup, CSS, HTML, WordPress, PHP
  • Manager of Version Control Systems/C++ Developer

    2005 - 2006
    • Led the integration management effort for all Movistar prepayment projects (Spain and Latin America) and the administration of several Linux and Solaris CVS servers.
    • Contributed to the implementation of new features for the Movistar Spain prepayment project. This involved C++ multi-architecture development and an extensive use of C++ templates.
    Technologies: C++, CVS
  • Web Developer, Project Leader, Systems and Database Manager.

    2003 - 2005
    Desarrollo y Recursos
    • Contributed to the administration, automation, and modernization of web (Apache+MySQL+PHP) and mail servers (Sendmail + Dovecot). Helped define policies for security, configuration management, development, and backups.
    • Developed a custom workflow and file management system for San Carlos Clinic Hospital (Madrid, Spain) using PHP for web programming and FDF for printable/electronic forms.
    • Designed and implemented an online showcase.
    • Analyzed, designed, and implemented customized services for www.iea.es.
    • Worked on the analysis, design, and implementation of a service for getting optimal routes between museums.
    Technologies: JavaScript, Web Hosting & Domain Setup, Dovecot, Apache, Sendmail, Debian, PHP
  • Co-owner/System Manager/Software Developer

    2000 - 2003
    Advanced Software Production Line
    • Helped install, manage, support, and boost security in Debian GNU/Linux servers and firewalls for small and medium enterprise environments.
    • Managed projects and analyzed, designed, and implemented AF-Architecture, a multi-tier modular architecture for enterprise software development under GPL open license. The project web page was programmed using a PHP-based app, TYPO3.
    • Analyzed, designed, and implemented a CMS system for the firm web page (www.aspl.es) using PHP.
    Technologies: Web Hosting & Domain Setup, C


  • Ama y Sirve

    Design and implementation of the website for this periodical bulletin, using WordPress, IssueM and other plugins. Using a responsive theme, the site was designed from scratch using Twig and Timber and a specific theme template was implemented for sending overviews of just-released issues using email marketing tools.

  • Linux Audit and Monitoring System

    I developed a Linux audit and monitoring system for a Canadian startup based on a pre-loaded library and PAM module that captured all the executed commands and their generated output.

  • Hyperbaric Store

    I developed the website from scratch, translating Photoshop mockups to HTML+CSS+JavaScript and using and customizing WordPress and WooCommerce.

  • Reporting System for Canal de Isabel II

    New report generation system for Canal de Isabel II, the main public water supplier in Madrid, Spain.

    Back end: C#, ASP.NET, MVC Framework, NHibernate, and Microsoft Excel.

    Front end: Single-sage Application using React and Bootstrap.

  • Nautilus: Web-based Operational Assistance System

    Main designer and developer of this modular web system that provides all needed features for supporting infrastructure operation and exploitation: event and incident management, fleet management, stock control, preventive and corrective maintenance, and shift management and works management. Different modules can be installed based on the requirements for each project.

  • SIDERA Reports: Web-based Reporting System for SICE's ITS Solution

    Main designer and developer of this web-based report system for SICE's ITS solution. This solution provides several reports related to traffic management that are shown on the web or can be exported to Excel or PDF formats.

  • Fundación MAIOR Website

    Web page for an NGO using WordPress with several plugins and WooCommerce for the online shop.

  • GnoMint: Open-source Tool for the Management of an X.509 Certification Authority

    Project leader and main developer.

    GnoMint is a tool for easily creating and managing certification authorities. It provides fancy visualization of all the pieces of information that pertain to a CA, such as x509 certificates, CSRs, and CRLs. GnoMint is currently capable of managing a CA that emits certificates that are able to authenticate people or machines in VPNs (IPSec or other protocols), secure HTTP communications with SSL/TLS, authenticate and cipher HTTP communications through Web-client certificates, and sign or crypt email messages. It's programmed in C using GTK+, SQLite and GnuTLS libraries.

    The project was created as the final-year project of my master's degree in computer science engineering.

  • Kelly Doe Studio Website

    A website based on WordPress software. The website was mainly based on pictures of designs made by the studio. The base template was totally transformed, so the main page showed a very different grid-based layout for the main page.

  • Calculation Engine for Damdata: Dam Auscultation SCADA

    Design and full implementation of a calculation engine programmed in Java for DamData: Ofiteco's specialized dam auscultation SCADA. The formulas are expressed in a formula definition language that is defined formally through lexical and syntax grammar. These formulas are compiled to grammar trees through compiler classes generated using ANTLR. The formulas are invoked by the SCADA and allow different calculations using current and historical data.

  • Madrid Calle-30 Urban Tunnels

    In the context of the construction of Madrid Calle-30 tunnels (a 47 km urban tunnel network) and the development of its control system, I was responsible for analyzing, designing, and developing the ventilation algorithms for activating and controlling the different fans and ventilation-related equipment in the tunnels, following the guidelines marked by experts in the field. I also worked on improving the scalability and robustness of SICE's RCUs (Linux embedded systems based on x86 architecture) so that they could manage and control more than 9,000 analog and digital inputs and outputs.

  • Employee Portal for Hospital Clínico San Carlos (Madrid)

    The system allows employees to start different procedures (asking for vacation, notifying of changes in family situation, taxes, etc.) that involve several steps of bureaucracy. In every step, the assigned group of people are notified about the pending actions, allowing them to interact with the application.

    Used PHP and MySQL in the server and PDF and FDF for the forms.

  • Routing Calculator for Huexpo.net

    Amidst the development of an institutional website for the different museums in the province of Huesca (Spain), I developed a routing engine for calculating optimal routes for visiting the different selected museums. Based on the traveler's algorithm, the different routes were pre-calculated for ensuring a fast response to the user.

  • Developer’s Guide to Open Source Licenses (Publication)
    Many developers often overlook, or do not thoroughly think through the implications of open source licenses. Whether you’re planning to open source your own project under one of these licenses, or you intend to integrate some other open source project into one of your own, it’s important to have at least some knowledge of what these licenses are, how they may affect your projects, and how they complement or contradict one another. In this article, Toptal engineer David Marín gives us a comprehensive guide to some of the most popular open source licenses, and several rules of thumb to follow when choosing a license for future open source projects.


  • Languages

    PHP 5, HTML, PHP, C, HTML5, JavaScript, PHP 7, C++, CSS3, CSS, Bash, Bash Script, SQL, Visual Basic 6 (VB6), C#, Java
  • Frameworks

    Symfony 2, Symfony, .NET, BEEP, ASP.NET MVC, Selenium, Bootstrap 3, ASP.NET MVC 4, NHibernate
  • Tools

    ACF Pro, Advanced Custom Fields (ACF), Subversion (SVN), CVS, AffiliateWP, GitHub, Bitbucket, GTK+, Exim4, Apache, DataTables, Redmine, Braintree SDK, Sendmail, Handsontable, Git, Bower, SoapUI, Nagios, ANTLR, Turbo Pascal, Composer, Microsoft Visual Studio, Google Analytics, Infusionsoft
  • Platforms

    WooCommerce, WordPress, Debian Linux, Linux, Ubuntu, LAMP, Marketo, Debian, Azure, Docker, Embedded Linux, Android, Oracle, Windows, Amazon Web Services (AWS), Amazon EC2, VWO, WordPress Theme Design
  • Storage

    WP Engine, JSON, MariaDB, PostgreSQL, MySQL, MySQL Server, Databases, Microsoft SQL Server, Amazon S3 (AWS S3)
  • Other

    APIs, Web Hosting, Web Hosting & Domain Setup, Domains & Hosting, Local Hosting, Embedded Software, Unix Shell Scripting, gnoMint, WordPress Plugins, WooCommerce Subscriptions 2, Content Management Systems (CMS), Legacy Code, Legacy Software, CAPTCHA, Ajax, GNU, TCP/IP, X.509, SOAP, Client-server Model, Payment APIs, Payment Gateways, Technical Leadership, Technical Reports, Architecture, BrainTree, Query Composition, Query Optimization, Linux Server Administration, Stripe Payments, Back-end Development, Back-end, Infoplus WMS, SCADA, Dovecot, Image Manipulation, Embedded Systems, Linux Kernel Drivers, eCommerce, User Interface (UI), Payment Security, Shops, Search, Responsive Design, Responsive UI, Email Marketing, Email Marketing Automation, WordPress Themes, Google SEO, Organic SEO, SEO Tools, Data Visualization, Regular Expressions, WordPress Design, Front-end, Front-end Development
  • Libraries/APIs

    jQuery DataTables, Braintree API, Doctrine, jQuery UI, jQuery, React, Stripe API, WooCommerce API, Stripe, Twitter API, OpenStreetMap API, LeafletJS, WordPress API, WordPress REST API, Highcharts, Infusionsoft API
  • Paradigms

    Model View Controller (MVC), Web Architecture, Hosting, Unit Testing, Responsive Layout, Responsive, Search Engine Optimization (SEO), Conversion Rate Optimization (CRO)
  • Industry Expertise

    IT Security, Security


  • Certificate in Software Security
    2015 - 2015
    Coursera (facilitated by the University of Maryland) - Online
  • Master's Degree in Computer Science
    1998 - 2003
    Universidad Politécnica de Madrid - Madrid, Spain

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