Juan Pablo Carzolio

Juan Pablo Carzolio

CS Engineer – Full-stack developer




I’m a versatile and dependable “full stack” software developer from Argentina (UTC-3), with an Engineering degree in Computer Science and 10 years of professional experience. I’m quite experienced in vanilla JavaScript and PHP, as well as HTML/5, CSS/3, and SQL. Other skills and experience include React, jQuery, Laravel, Memcached, RESTful APIs, AWS cloud infrastructure and Linux servers, to name a few. I have excellent communications skills, bilingual-level English, and love challenges and opportunities to grow, learn, and to apply reasoning and creativity to come up with ideas and solutions. The more thinking is involved, the more I like a project.

Despite being primarily focused on web technologies, I’m also interested in other areas, such as games, computer graphics, mobile apps, and embedded systems.


Full Stack Engineer (freelance, via Toptal) at

May 2017 – Present (9 months)

  • Worked in an agile team environment, having daily standup meetings, tracking tasks using JIRA, etc.
  • Designed and implemented most of the API-facing and Redux logic of the SPA.
  • Designed and implemented the overall visual structure of the app, as well as many of the views and components.
  • Worked together with another front-end developer, reviewing each other’s code and discussing important topics together to find the best solutions.
  • Wrote unit tests and test helpers for most major functions and React components, using Jest and Enzyme.
  • Made smaller contributions and suggestions for the app back-end too, written in Java (Spring Boot).
  • Designed the overall app authorization system based on permissions and roles.
  • Technologies: React, Redux, JavaScript, ES6, Bootstrap, Webpack, Eslint, yarn, Lodash, Jest, Enzyme

Full Stack Engineer at Meridix (freelance, via Toptal)

Mar 2017 – Oct 2017 (8 months)

  • Migrated a very old PHP codebase to Laravel 5.
  • Redesigned and migrated the UI using Bootstrap, custom CSS, Less, jQuery and “vanilla” JS.
  • Fixed bugs and solved migration issues.
  • Rewrote many hardcoded SQL queries using Eloquent and/or parameter binding.
  • Technologies: PHP, Javascript, Laravel 5, Bootstrap 3, Less, jQuery, Chart.js, Redis

Architect and Lead Developer at Vistrata (via Toptal)

May 2016 – Jan 2017 (9 months)

  • Took over an existing base project, which I improved and extended.
  • Designed and Implemented a lightweight data access layer to replace a slow custom ORM layer.
  • Designed and implemented a JavaScript component to efficiently render Gantt-like bars from input row data of unlimited size.
  • Implemented Ag-Grid throughout the app to display grids, using custom code to integrate with my Gantt component, add unsupported features, etc.
  • Designed and implemented a technique to batch CRUD operations on the front-end and process them asynchronously on the back-end, allowing for seamless editing with autosave (Google Docs style) and enabling offline editing.
  • Designed the basics of an advanced data revision control system to be implemented in the DB, which is efficient in both space and time.

Freelance Software Developer at CertaPet (via Toptal)

November 2015 – April 2016 (5 months)

  • Worked with the founders to design and build a platform MVP that would allow their existing business concept to scale.
  • Suggested a split architecture consisting of a PHP back-end with a REST API, and a SPA front-end. Designed the DB schema and implemented all of the back-end and API.
  • Integrated several third-party services, including Stripe, Mandrill, Wufoo, WebMerge, and HelloSign, using their APIs.
  • Designed and built the back-end infrastructure in AWS, using RDS, EC2, S3, and IAM.

Freelance Software Developer at 6V

May 2011 – Aug 2017 (6 years)

  • Joined and led a small remote team that worked on feature development, maintenance, bug-fixes, optimization and testing of a high traffic (2M+ DAU) application on the Facebook Platform
  • Worked on maintenance, optimization and migration of the app’s cloud infrastructure based on AWS and Rightscale, including load balancing (ELB), webserver arrays, memcached servers, cron servers, RDS, S3, Route53, CloudFront
  • Developed using PHP, HTML, CSS, JavaScript, Facebook API, Memcached, MySQL

FB App Developer/Owner

November 2009 – June 2011 (1 year 8 months)

  • Owned and developed several applications on the Facebook Platform (including two games) reaching a total traffic of 70k DAU (daily active users) at their peak
  • Developed an ad network mixing system that maximized revenue by optimizing each network’s traffic share based on their performance (eCPM)
  • Developed a custom analytics system to track app signals (events) based on users’ country, language, gender and date, allowing for A/B testing of certain features and UI choices
  • Developed using PHP, HTML, CSS, JavaScript, Actionscript/Flash, Facebook API
  • Created and edited all original and derived artwork with Photoshop

Developer at Globant

June 2008 – November 2009 (1 year 6 months)

  • Designed and implementated a system to transfer large files over HTTP from within web applications, with advanced features like pause, resumption and recovery of uploads and downloads.
  • Designed and implementated a system to transcode media files (images and video) for client applications that featured media previews.
  • Java & web development, using among others: J2SE, J2EE, applets, Servlets, Spring, Spring MVC, Hibernate, Maven, Jabsorb, JSP, HTML, CSS, JavaScript, Ajax, PHP, Apache, Tomcat, OC4J, Oracle 10g.

Freelance Web Developer

January 2007 – April 2014 (7 years 4 months)

  • Developed websites using HTML, JavaScript, PHP and Flash
  • Acquired knowledge of and experience in base web technologies

Developer at ITBA

September 2006 – December 2006 (4 months)

  • Designed and implemented an algorithm for classroom assignment based in heuristics
  • Implemented a reservation service and DAO within a Hibernate/Spring architecture


Instituto Tecnológico de Buenos Aires (ITBA)

Engineer’s Degree in Computer Science, 2003 – 2007

Skills & Expertise

Programming languages

  • Proficient in (and currently using):
    JavaScript, PHP, HTML, CSS
  • Proficient in (but not used in a while):
    Java, C
  • Basic knowledge of (and not used in a while):
    ActionScript, Asm (x86), Perl, Lisp

Other skills

React, JSX, Redux, Bootstrap, jQuery, Laravel, MySQL, Memcached, Linux (Ubuntu, CentOS), Apache, Amazon Web Services (AWS), Git, SVN


  • Spanish (native)
  • English (bilingual proficiency)

I hold 3 certifications from the University of Cambridge Local Examinations Syndicate (now Cambridge English Language Assessment), including the CPE (Certificate of Proficiency in English, their highest certification).


music, guitar, mathematics, programming, algorithms, AI, bitcoin, trading algorithms, quantum computing, games, 2D, 3D, audio, graphics, video, physics, electronics, bioinformatics, trekking, backpacking, ski, business opportunities

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