Julio Marquez, Developer in Valencia, Spain
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Julio Marquez

Verified Expert  in Engineering

Full-stack Developer

Valencia, Spain
Toptal Member Since
July 15, 2020

Julio has been a passionate full-stack developer for 11 years. He's architected complex web apps, led teams, and spoken at conferences in his field. Julio loves developing open-source projects and has +2,600 GitHub stars (JavaScript). He enjoys freelancing because it allows him to bring his expertise to new clients, discover challenging projects, and meet new people in the industry. Julio thrives in distributed teams and always emphasizes commitment, quality, and clear communication.


Toptal Client
Vue, Nuxt.js, CSS, Git, Content Management Systems (CMS), Headless CMS...
Jest, Firebase, Vuex, TypeScript, Amazon S3 (AWS S3), GitHub, React...
Jest, Vuex, TypeScript, GitHub, React, HTML, Pandas, Express.js, Django ORM...




Preferred Environment

GitHub, Git, MacOS, Ubuntu, GitLab, Visual Studio Code (VS Code)

The most amazing...

...thing I've built is Mapset, an innovative online tool for managing screens in different mainframe coding languages, 15x faster than any other tool available.

Work Experience

Software Developer

2020 - 2021
Toptal Client
  • Migrated a WordPress blog to static generated Website using Nuxt.js for an oil and gag analytics company.
  • Reworked main website following pixel-perfect design from Figma to HTML/CSS.
  • Incorporated Sanity CMS, a headless CMS, to support blog posts and global settings for the website.
  • Guided and supported the website deployment to AWS Amplify Hosting.
Technologies: Vue, Nuxt.js, CSS, Git, Content Management Systems (CMS), Headless CMS, Responsive Design, Search Engine Optimization (SEO), Analytics, Amazon Web Services (AWS), WordPress

Co-founder | Full-stack Developer

2015 - 2019
  • Co-founded a web development agency with the primary focus of standing out from the crowd by executing high-performance websites and mobile apps, combining an eye toward transparency, inspection, and adaptation.
  • Contributed to bringing together an extraordinary experience by leveraging knowledge and ideas to build processes around quality and passion while working with exceptional people.
  • Executed, as a team, more than 42 projects, including dynamic web and mobile apps, eCommerce sites, and corporative sites.
  • Drew upon a combination of a strong passion and continuous innovation and recognized that we can always be better at creating products and open source projects to improve the web developer community.
  • Grew from two to 14 employees in eleven months and landed contracts with small and large companies.
Technologies: Jest, Firebase, Vuex, TypeScript, Amazon S3 (AWS S3), GitHub, React, NativeScript, HTML, Pandas, Express.js, Django ORM, NPM, Sass, Django, REST APIs, Git, Python, Node.js, CSS, JavaScript, Serverless, Open Source, Vue, Nuxt.js, Bootstrap, jQuery, Back-end, HTML5, Front-end, Full-stack, Next.js, CSS3, PHP

Full-stack Developer

2008 - 2016
  • Created a front-end admin template that earned +4.7 stars out of 5 on Themeforest; it was fully responsive and cross-browser with Bootstrap and jQuery. Included easy-to-use components and a huge collection of plugins.
  • Built more than 20 high-performance websites, including dynamic web applications, eCommerce, and corporative sites.
  • Developed the initial layouts and built the front ends with HTML, CSS, JavaScript, jQuery, Ajax, and Angular/React.
  • Developed a back end using PHP, Python, MySQL, and PostgreSQL.
  • Integrated various third-party APIs, including Google Map APIs, Google Analytics, and Facebook APIs.
Technologies: Jest, Vuex, TypeScript, GitHub, React, HTML, Pandas, Express.js, Django ORM, NPM, Sass, Django, REST APIs, Git, Python, Node.js, CSS, JavaScript, Serverless, Open Source, Vue, Nuxt.js, Bootstrap, jQuery, Back-end, HTML5, Front-end, Full-stack, Angular, CSS3, PHP

Scientific Programmer

2014 - 2015
Geochemical Research and Engineering, Inc.
  • Worked on a research team of computational expertise to solve problems in reservoir simulation and fluid/gas injection.
  • Helped to create a unique-and-innovative product in the oil industry that perform complex computational simulation for aqueous speciation and mineral precipitation, based on the extensive and patented multi-year research of the company's founder.
  • Worked in a high-performance team focused on computer simulations to solve the oil industry's most outstanding and difficult engineering calculations and computing processes.
Technologies: REST APIs, Git, Python, Back-end, C#, MATLAB, Visual Studio

Research Assistant

2010 - 2015
Satellite Geodesy and Seismotectonics Laboratory
  • Researched and developed computational simulations in the area of seismotectonic.
  • Planned, executed, processed, and analyzed georeferenced data from GPS measurements.
  • Adjusted geodetic control networks using satellite techniques and computational models and analysis.
  • Published multi-year research findings in the Geophysical Journal International, a scientific journal published by Oxford University Press.
Technologies: Pandas, Jupyter, REST APIs, Git, Python, JavaScript, Back-end, CSS3

Statusfy | A Marvelous Open-source Status Page system

Statusfy is a status-page system that's easy to use and deploy to a variety of hosting services. The goal is to lower costs and complexity by providing a more straightforward and versatile open-source alternative.

It was designed to generate a system that works as a progressive web application with the JAMstack architecture in mind and fast static generation. With these approaches, I wanted the users to enjoy a status-page system that gives better performance, higher security, cheaper hosting, and better user experience.

I'm the author of this tool. I created the original project architecture, the back end, front-end code, and the visual identity, as well as an easy to use CLI (command-line interface) that improves the interaction and the building process of the system.


A new, innovative, and dynamic tool designed for managing screens in different mainframe coding languages. Mapset makes designing the mainframe screens commonly used in the banking industry less painful. Mapset became 15x faster than conventional methods or any other tool available.

It's cloud-based, inexpensive, very easy to use, and users don't need to be experts in the industry.

I created the project architecture as well as the back-end code. I led the front-end development while constantly communicating with the mainframe engineers, who were experts in the banking and insurance industry. We discovered that the core of the product had to be a web application with a dynamic interface using the power of modern web browsers for the main tasks of the process.

Besides, the serverless execution for the file conversion tasks was the best choice for reducing the overhead of servers: on-demand implementation, parallelism, and lower costs.

Everything about the project was tested and documented to ensure the security and stability of the management of customer information.

Nuxt Optimized Images

I created a Nuxt.js module to automatically optimizes images (JPEG, PNG, SVG, WebP, and GIF).

Module Features:
• Reduce image sizes by up to 60%.
• Improve loading speed by providing progressive images and converting JPEG/PNG images to WebP on the fly for an even smaller size.
• Resize images or generate low-quality image placeholders (LQIP) and extract the dominant colors of it.
• Content hash to the file name so images can get cached on the CDN level and in the browser for a long time.
• Inline small images to save HTTP requests and additional roundtrips.

The North Andes and the Caribbean and South American Plate Interaction

In college, I worked as a research assistant in the Satellite Geodesy and Seismotectonics Laboratory of the Simon Bolivar University (Caracas, Venezuela). We worked for four years on a very interesting project: finding the interaction of the North Andes plate with the Caribbean and South American plates in northwestern South America from GPS geodesy and seismic data.

The work done on this project taught me many things: statistics, data analysis, interpretation of third-party research in addition to the importance of teamwork, great communication, and the commitment to your boss/supervisor and the community to whom you're trying to give a scientific outcome.

This research was carefully executed and went through a rigorous review process to be published in the Geophysical Journal International, a scientific journal published by Oxford University Press on behalf of the Royal Astronomical Society and the Deutsche Geophysikalische Gesellschaft.
2006 - 2014

Bachelor's Degree in Geophysical Engineering

Simon Bolivar University - Caracas, Venezuela


Latin America Representative

American Association of Petroleum Geologists


Student Chapter Excellence Award

Society of Exploration Geophysicists


Leadership Symposium Travel Grant Award

Chevron and the Society of Exploration Geophysicists


Vue 2, jQuery, Vue, Node.js, React, Pandas, REST APIs, Django ORM, Vuex, Matplotlib, NumPy, SciPy, OpenCV


Pytest, Jupyter, Git, NPM, Gulp, GitHub, GitLab, MATLAB, Sketch, Visual Studio, Miva Merchant


Nuxt.js, Bootstrap, Django, Next.js, Tailwind CSS, Express.js, Jest, Vuetify, React Native, NativeScript, Flask, Redux, Angular


Clean Code, Testing, REST, Unit Testing, Search Engine Optimization (SEO), Test-driven Development (TDD), Serverless Architecture


HTML5, HTML, JavaScript, Python, CSS3, Sass, CSS, TypeScript, GraphQL, PHP, C#


Firebase, Visual Studio Code (VS Code), Docker, Amazon Web Services (AWS), MacOS, WordPress, Google Cloud Platform (GCP)


Amazon S3 (AWS S3), MongoDB, PostgreSQL, MySQL, Google Cloud Datastore

Industry Expertise

Project Management


Team Leadership, Teamwork, Open Source, GPS, Serverless, Georeferencing, Front-end, ESLint, Full-stack, Back-end, Code Architecture, Content Management Systems (CMS), Headless CMS, Responsive Design, Scientific Computing, University Teaching, Research, Challenge-based Learning, Team Building, Geophysics, Applied Research, English-Spanish Translation, Material Design, PWA, Progressive Web Applications (PWA), eCommerce, eCommerce Platforms, Analytics, Google Cloud Functions

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