Marlon Mantilla, Developer in Medellín - Antioquia, Colombia
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Marlon Mantilla

Software Developer

Medellín - Antioquia, Colombia

Toptal member since July 21, 2014

Expertise
Front EndFull-stackBack-end DevelopersREST APIGitHubCSSHTML5JavaScriptRubyReact.jsTypeScriptjQueryAWS
Bio

Marlon is a full-stack developer with 10+ years of professional experience in software development. As a developer, Marlon's expertise is in the implementation of best practices in creating apps. He's worked for companies that offer healthcare IT services. He has built chatbots with React and also web apps for administration. Marlon has strong expertise in Ruby on Rails and Node.js as well.

Portfolio

Cartwheel
Ruby on Rails (RoR), Aptible, React, Next.js
MedArrive
Ruby on Rails (RoR), React, React Native, Expo, Electronic Health Records (EHR)
Dig Deep, Inc.
React Native, Expo, PostgreSQL, TypeScript, Node.js

Experience

  • Ruby - 10 years
  • Ruby on Rails (RoR) - 10 years
  • CSS - 10 years
  • HTML5 - 10 years
  • JavaScript - 10 years
  • React - 6 years
  • Node.js - 6 years
  • React Native - 5 years

Preferred Environment

MacOS, Unix, Git, Visual Studio Code (VS Code), Node.js

The most amazing...

...product I've developed is a social network for managing community groups. It features a cool calendar widget and allows users to embed the calendar.

Work Experience

Senior Full-stack Engineer

2026 - PRESENT
Cartwheel
  • Delivered full-stack capabilities on Cartwheel’s healthcare platform—Rails services, background processing, and the React portal at /v2—supporting K–12 schools and families through mental health access and care coordination workflows.
  • Owned features end-to-end across API contracts, portal UI work, Sidekiq-style async workflows, and production operability, ensuring changes shipped with authorization boundaries, safer data access patterns, and clear failure behavior.
  • Built and refined portal experiences aligned to product requirements and the shared component approach, keeping flows cohesive across web surfaces as the organization scales school and family-facing workflows.
Technologies: Ruby on Rails (RoR), Aptible, React, Next.js

Senior Full-stack Engineer

2021 - 2025
MedArrive
  • Led delivery for a React Native (Expo) mobile experience used by field clinicians for visit scheduling and status updates, turn-by-turn routing, and location-aware notifications tied to approach-to-patient workflows.
  • Built and shipped Ruby on Rails and React features on a clinical field-care platform supporting ambulatory visits, operations workflows, and partner-facing tooling, including end-to-end ownership from API changes through production rollout.
  • Partnered tightly with product, design, and clinical stakeholders to translate regulated healthcare requirements into iterative releases, balancing speed, safety, and maintainability on a large production codebase.
Technologies: Ruby on Rails (RoR), React, React Native, Expo, Electronic Health Records (EHR)

Full-stack Engineer

2024 - 2024
Dig Deep, Inc.
  • Shipped consumer-facing mobile product work for the Mental app using React Native and TypeScript, emphasizing stable navigation, predictable state management, and maintainable module boundaries as the product iterated quickly.
  • Partnered with design to keep UI consistency and interaction patterns coherent across core onboarding and session flows, reducing fragmented one-off screens as the app scaled feature surface area.
  • Strengthened engineering fundamentals for mobile delivery (error handling, instrumentation hooks, and regression protection on critical paths) so chat and core loops could ship without compromising app stability.
Technologies: React Native, Expo, PostgreSQL, TypeScript, Node.js

Front-end Developer

2022 - 2023
MagicLinks, Inc
  • Maintained several internal reporting tools built with Next.js and Ruby On Rails.
  • Tracked and fixed current platform production bugs.
  • Optimized code and proposed refactoring for old repositories.
Technologies: React, Ruby on Rails (RoR), JavaScript, Jira, Webpack 4, User Interface (UI), User Experience (UX), HTML, CSS, Figma, Next.js, Docker, PostgreSQL, Architecture, Full-stack, Back-end, UI Components, Design Systems, Python, Tailwind CSS, Product Management, Stripe, eCommerce, Mobile Development, Amazon Web Services (AWS), Mobile, Expo, Google Play Console, React Router, React Navigation, CircleCI, Sentry, GitHub, Node.js, Express.js, GraphQL, Artificial Intelligence (AI), Full-stack Development, UI Design, HIPAA Compliance, Vite, Claude Code, Electronic Medical Records (EMR), API Integration

Senior React | React Native Developer

2021 - 2022
Animo Services LLC
  • Helped build a Flutter app for fintech Glorifi from scratch. Built base UI components.
  • Helped implement Okta authentication for authentication and authorization.
  • Worked with product owners to manage a small team for building fintech integration. Helped implement Plaid into the app flows for extracting financial insights per user.
Technologies: React, React Native, Architecture, Mobile UX, APIs, Integration, REST APIs, Apollo, TypeScript, User Interface (UI), User Experience (UX), Figma, PostgreSQL, Docker, Technical Leadership, Vanilla JS, Full-stack, Back-end, UI Components, Design Systems, Amazon Web Services (AWS), Product Management, Flutter, Stripe, iOS, Android, Mobile Development, Mobile, Expo, Google Play Console, React Router, Emotion Library, React Navigation, CircleCI, Google Maps, Sentry, GitHub, Node.js, Express.js, GraphQL, Full-stack Development, UI Design, HIPAA Compliance, Vite, Claude Code, Strapi, Google Cloud Platform (GCP), Electronic Medical Records (EMR), API Integration

Senior Full-stack Developer

2018 - 2020
Syllable
  • Developed a React admin tool for making video conferences.
  • Set up a CI integration with Docker, CircleCI, and AWS, allowing us to automate a deployment process for a client.
  • Made a chatbot with React connected to an API that allowed patients to communicate with their hospital.
Technologies: Asana, Git, Node.js, React, JavaScript, HTML5, Front-end, Front-end Build Tools, React Native, Redux, APIs, Continuous Integration (CI), Continuous Delivery (CD), Scrum, CSS3, Agile Software Development, SendGrid API, Visual Studio Code (VS Code), SQL, REST APIs, Apollo, TypeScript, Jira, Webpack 4, User Interface (UI), User Experience (UX), Figma, PostgreSQL, Docker, Next.js, Mapbox, Architecture, Technical Leadership, MySQL, Vanilla JS, Full-stack, Back-end, UI Components, Design Systems, Python, Amazon Web Services (AWS), Tailwind CSS, Mobile Development, Mobile, Expo, React Router, Emotion Library, React Navigation, CircleCI, Google Maps, Sentry, GitHub, Express.js, GraphQL, Full-stack Development, UI Design, Electronic Medical Records (EMR), API Integration

Full-stack Developer

2016 - 2017
Infuse.us
  • Implemented features in a hybrid Angular/Cordova app.
  • Added features to a Rails API.
  • Fixed bugs and refactored for old modules.
Technologies: Angular, Ruby on Rails (RoR), Ruby, HTML5, Front-end, Front-end Build Tools, React Native, Redux, APIs, Continuous Integration (CI), Continuous Delivery (CD), Scrum, CSS3, Agile Software Development, SendGrid API, Visual Studio Code (VS Code), React, REST APIs, Apollo, TypeScript, Jira, Webpack 4, User Interface (UI), User Experience (UX), Figma, PostgreSQL, Docker, Mapbox, MySQL, Vanilla JS, Full-stack, UI Components, Design Systems, Python, Tailwind CSS, Stripe, eCommerce, Mobile Development, Amazon Web Services (AWS), Mobile, React Router, CircleCI, Google Maps, Sentry, GitHub, Node.js, Full-stack Development, API Integration

Full-stack Developer

2015 - 2016
Diagnotes.com
  • Added features to the Rails API.
  • Added features to a front-end application based in Angular.
  • Fixed bugs and refactored code.
  • Wrote automated tests.
  • Maintained a Scrum board and added tasks.
Technologies: Angular, Ruby on Rails (RoR), Ruby, HTML5, Front-end, Front-end Build Tools, React Native, APIs, Scrum, CSS3, Agile Software Development, SendGrid API, Visual Studio Code (VS Code), React, REST APIs, Apollo, Jira, Webpack 4, User Interface (UI), User Experience (UX), PostgreSQL, MySQL, Full-stack, Design Systems, GitHub, Full-stack Development

Full-stack Developer

2014 - 2015
Golazzos
  • Built site markup from scratch and implemented React components.
  • Developed the site's API and set up deployment with Capistrano.
  • Implemented a prize system for workers using the site.
Technologies: CSS, JavaScript, React, Ruby on Rails (RoR), HTML5, Front-end, Front-end Build Tools, APIs, Scrum, SendGrid API, REST APIs, Webpack 4, PostgreSQL, Design Systems, GitHub, Full-stack Development

Ruby on Rails Developer

2014 - 2015
Cellbreaker
  • Built a Ruby on Rails administration panel.
  • Created a scraper tool for fetching information.
  • Handled admin tool styling and layout.
  • Developed Backbone.js models and set up components.
Technologies: Backbone.js, JavaScript, Ruby on Rails (RoR), Front-end, Scrum, REST APIs, GitHub, Full-stack Development

Senior Ruby on Rails Developer

2013 - 2014
Globant
  • Set up an application deployment process with Capistrano.
  • Built a Backbone.js front end and wrote tests in RSpec and Capybara.
  • Refactored legacy Rails application code and wrote markup and CSS.
Technologies: Ruby on Rails (RoR), GitHub, Full-stack Development

Ruby on Rails Developer

2010 - 2012
Koombea
  • Created an embeddable jQuery calendar widget.
  • Set up background jobs for sending huge email campaigns.
  • Set up Capistrano deployment for projects.
  • Wrote HTML and CSS for Rails apps.
  • Managed teams as Scrum Master.
Technologies: Backbone.js, jQuery, CSS3, HTML, Ruby on Rails (RoR), GitHub

Senior Java Developer

2010 - 2010
Extreme Technologies
  • Built JSP web interfaces.
  • Ensured consistency on SQL queries.
  • Built a GPS interface.
  • Rewrote legacy code and implemented new features.
  • Built a location API.
Technologies: JavaScript, CSS, HTML, Jakarta Server Pages (JSP), GitHub

PHP Developer

2008 - 2010
Evoluziona
  • Refactored legacy code.
  • Set up a Cake PHP project.
  • Wrote JavaScript/jQuery reusable components.
  • Worked closely with designers and programmers, applying design comps to various pieces of functionality.
  • Developed plug-ins for jQuery and MooTools.
Technologies: JavaScript, CSS, HTML, PHP, GitHub

Experience

Expenses Tracker App

An expense tracking application build with AngularJS and Rails.

Nooddle

Is a recipe recommendation search engine system. Users will search ingredients that they have in their fridge or kitchen. I was in charge of the front-end application with Angular.

Education

2004 - 2009

Master's Degree in Computer Engineering

Universidad Del Norte - Barranquilla, Colombia

Skills

Libraries/APIs

React, SendGrid API, jQuery, REST APIs, React Navigation, Node.js, Face.com API, jQuery UI, Backbone.js, React Router, Stripe, Emotion Library, Google Maps

Tools

Front-end Build Tools, Expo, Sentry, GitHub, Adobe Photoshop, Git, Sublime Text 3, Jira, Webpack 4, Figma, CircleCI, Claude Code, Asana

Languages

HTML, CSS, HTML5, JavaScript, CSS3, Ruby, TypeScript, PHP, Python, CoffeeScript, SQL, GraphQL, C#

Frameworks

Ruby on Rails (RoR), React Native, Redux, Tailwind CSS, ZURB Foundation, Ember.js, Vanilla JS, Flutter, Express.js, Jakarta Server Pages (JSP), Angular, Hapi.js, Django, Next.js, .NET

Paradigms

Scrum, Mobile Development, UI Design, HIPAA Compliance, Agile Software Development, Continuous Integration (CI), Continuous Delivery (CD), Metaprogramming

Platforms

Amazon Web Services (AWS), Mobile, Visual Studio Code (VS Code), MacOS, Unix, Linux, Docker, Mapbox, iOS, Android, Google Cloud Platform (GCP), Aptible

Storage

PostgreSQL, MySQL, MongoDB, Microsoft SQL Server

Other

Front-end, APIs, Architecture, Technical Leadership, Full-stack, Back-end, UI Components, Design Systems, Full-stack Development, Electronic Medical Records (EMR), API Integration, Ember CLI, Apollo, User Interface (UI), User Experience (UX), Product Management, eCommerce, Google Play Console, Mobile UX, Integration, Artificial Intelligence (AI), Vite, Strapi, Electronic Health Records (EHR)

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