Alex Casillas, Developer in Córdoba, Spain
Alex is available for hire
Hire Alex

Alex Casillas

Verified Expert  in Engineering

Bio

Alex is a senior software engineer and a self-taught technology expert with a solid track record in SaaS development. He is experienced in JavaScript and many other tools, such as React, React Native, Vue, Angular, SwiftUI, and C#. Alex also has a good handle on UI/UX design and loves learning new technologies and keeping his skills fresh and up-to-date.

Portfolio

Toptal, LLC
Node.js, React, Deno, Vite, Bun, JavaScript, TypeScript, HTML5, Design...
InAccord
Node.js, React, JavaScript, TypeScript, MobX, MobX-State-Tree (MST), PostgreSQL...
Hanzo Studio
Vue, Node.js, React, JavaScript, TypeScript, HTML5, Design, Dashboards

Experience

  • Laravel - 10 years
  • React - 10 years
  • Node.js - 10 years
  • TypeScript - 10 years
  • JavaScript - 10 years
  • MobX - 10 years
  • MobX-State-Tree (MST) - 10 years
  • React Native - 4 years

Availability

Part-time

Preferred Environment

MacOS, Windows

The most amazing...

...thing I've done is contribute to Toptal's talent and staff platforms as a senior and principal engineer for the past 3.5 years.

Work Experience

Senior Front-end Developer

2021 - 2024
Toptal, LLC
  • Served as a senior and principal engineer at Toptal for 3.5 years, collaborating with teams of different sizes and people from very different places worldwide.
  • Implemented the latest features for Toptal's talent and staff platforms and contributed as a front-end experience engineer, creating UI components for Toptal's React UI library, Picasso.
  • Created and managed the front-end infrastructure of Toptal's staff and talent platforms via DaVinci, Toptal's core package for handling mono repositories and SPAs.
  • Worked with TopKit, Toptal's shared utility package across different front-end projects, to share common utilities and toolkits.
  • Stepped up as an interim engineering manager when the need arose.
Technologies: Node.js, React, Deno, Vite, Bun, JavaScript, TypeScript, HTML5, Design, Dashboards

Senior Front-end Developer

2019 - 2020
InAccord
  • Designed and implemented a scalable front-end architecture using React, MobX, and MobX-State-Tree, ensuring maintainability and adaptability for future feature expansions.
  • Created an intuitive and responsive user interface that enhances user engagement and satisfaction, contributing to Accord's mission of enforcing execution excellence.
  • Built and integrated back-end services using Node.js and PostgreSQL, facilitating efficient data management and real-time synchronization between the front- and back-end systems.
  • Implemented performance optimization techniques, resulting in faster load times and a smoother user experience, which is crucial for Accord's deal execution platform.
  • Developed a reusable component library, promoting consistency across the application and accelerating the development process for new features.
  • Leveraged MobX and MobX-State-Tree to manage complex application states effectively, ensuring data integrity and reducing potential bugs.
Technologies: Node.js, React, JavaScript, TypeScript, MobX, MobX-State-Tree (MST), PostgreSQL, PostgREST, HTML5, Design, Dashboards

Front-end Engineer

2018 - 2019
Hanzo Studio
  • Developed several applications for different top-tier companies.
  • Created a full-featured onboarding system for a bank in Dubai.
  • Developed highly interactive and multimedia-rich web applications.
Technologies: Vue, Node.js, React, JavaScript, TypeScript, HTML5, Design, Dashboards

Full-stack Developer

2016 - 2017
Genially
  • Developed the interactive systems of Genially from scratch.
  • Worked closely with the CTO to plan features and architect the infrastructure.
  • Oversaw the launch of the new features, supporting the entire release process from the concept idea to the production phase.
Technologies: React, Node.js, Express.js, MobX, MobX-State-Tree (MST), MongoDB, jQuery, JavaScript, TypeScript, Material UI, HTML5, Design, Dashboards

Experience

Ziip.it

https://ziip.it/
A web application for sharing files easily and securely. Users can upload files for free, generate instant short links, and share with friends, family, or colleagues. The application is simple, fast, and requires no signup, making file sharing effortless.

Bookwriters

An app that uses artificial intelligence to boost the writing process. It transcribes voice recordings, generates summaries, offers writing suggestions, and extracts keywords, helping authors of all levels create better stories faster.

Cratebox

https://cratebox.io/
A fast, reliable, and extensive content delivery network designed to serve all of npm's vast repository of packages.

Using Cratebox, developers can instantly access any file from any package through a simple URL, enabling seamless integration and rapid deployment of dependencies across projects. Its high-speed global distribution network ensures minimal latency, making it ideal for developers who require efficiency and accessibility. With Cratebox, fetching files is effortless, streamlining workflows and improving productivity by reducing the time spent managing and downloading package dependencies.

Education

2016 - 2019

Bachelor's Degree in Computer Science

La Salle Open University - Barcelona, Spain

2016 - 2018

Higher-Level Technical Degree in Multiplatform Application and Web Development

IES Trassierra - Córdoba, Spain

2014 - 2015

Expert Coursework in Management and Web Application Development

Catholic University of Ávila - Ávila, Spain

Certifications

NOVEMBER 2020 - PRESENT

iOS SwiftUI

Design+Code

NOVEMBER 2018 - PRESENT

Ultimate Angular

Ultimate Angular

NOVEMBER 2018 - PRESENT

CSS Grid

CSSGrid.io

NOVEMBER 2018 - PRESENT

Advanced React Patterns

Frontend Masters

NOVEMBER 2018 - PRESENT

Fullstack Advanced React and GraphQL

AdvancedReact.com

NOVEMBER 2018 - PRESENT

RxJS Basics and Masterclass

Ultimate Courses

NOVEMBER 2017 - PRESENT

React for Beginners

ReactForBeginners.com

NOVEMBER 2017 - PRESENT

ES6 for Everyone

ES6.io

Skills

Libraries/APIs

Node.js, React, Inertia, MobX, MobX-State-Tree (MST), OpenAI API, RxJS, PostgREST, Vue, jQuery

Tools

NPM, Apache

Languages

JavaScript, TypeScript, HTML, CSS, PHP, HTML5, Java, C#, Swift

Frameworks

Laravel, Next.js, React Native, Android SDK, Angular, Material UI, ASP.NET Core, SwiftUI, Express.js

Platforms

Visual Studio Code (VS Code), MacOS, Windows, Android, Linux, DigitalOcean, iOS

Storage

MySQL, PostgreSQL, MongoDB, Amazon S3 (AWS S3)

Other

CSS Grid, Deno, Vite, Bun, Computer Science, Mathematical Analysis, Mathematical Logic, Cloudflare, OpenAI, OpenAI SDK, Streaming, Streaming Data, Design, Dashboards

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.

1

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring