Marcelo Biffara, Developer in Buenos Aires, Argentina
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Marcelo Biffara

Verified Expert  in Engineering

ChatGPT API Developer

Buenos Aires, Argentina
Toptal Member Since
January 20, 2015

Marcelo is passionate about software development and has known exactly what he wanted to do since childhood. He is a full-stack developer who enjoys writing in Ruby and JavaScript and has experience working with SQL and NoSQL databases and 3rd-party API integration. Marcelo has worked on successful projects, many of which involved high-concurrency platforms and websites.


10% Happier, Inc.
Svelte, Tailwind CSS, Ruby on Rails (RoR), Inertia, JavaScript, TypeScript...
MiTech Software Solutions Ltd
NestJS, Chatbots, WhatsApp, API Integration, REST API Clients
Lingo Live Language Services, Inc
Ruby on Rails (RoR), HTML, CSS, PostgreSQL, SQL, Heroku, Tailwind CSS, SendGrid...




Preferred Environment

Git, MacOS, Visual Studio Code (VS Code), Terminal, Chrome

The most amazing...

...thing I've worked on is a content processing online platform based on queues and workers that handles millions of incoming messages every day.

Work Experience

Svelte Developer

2024 - 2024
10% Happier, Inc.
  • Applied a new design to the web application and updated the Stripe integration.
  • Implemented Svelte together with Inertia to build the single-page application.
  • Used Linear for ticket management and oversaw the testing process for a successful launch.
Technologies: Svelte, Tailwind CSS, Ruby on Rails (RoR), Inertia, JavaScript, TypeScript, RSpec, Capybara, Git, reCAPTCHA


2024 - 2024
MiTech Software Solutions Ltd
  • Created a service for the client's CRM, enabling them to build a chatbot using WhatsApp Cloud API.
  • Built a NestJS service that interacts directly with the WhatsApp Cloud API, makes it easy to send text messages, templates, and quick reply buttons, and marks received messages as read.
  • Removed Twilio and its associated costs by interacting with the Meta WhatsApp Cloud API.
Technologies: NestJS, Chatbots, WhatsApp, API Integration, REST API Clients

Front-end Developer

2023 - 2023
Lingo Live Language Services, Inc
  • Developed a Rails app that manages coaching engagements for thousand of users using Tailwind CSS, Rails 7, PostgreSQL, and Redis.
  • Reviewed team's pull requests and deployed to production an app that serves the company's core business.
  • Helped improve the codebase by implementing Ruby interactors and best practices.
Technologies: Ruby on Rails (RoR), HTML, CSS, PostgreSQL, SQL, Heroku, Tailwind CSS, SendGrid, Redis

Full-stack Developer

2022 - 2023
Nextflag S.R.L.
  • Built a custom mailing library that lets users easily swap between mailing vendors.
  • Integrated Sendgrid's API to replace the default SMTP email Rails integration.
  • Created a custom device mailer that integrates with the custom mailing library.
Technologies: Ruby on Rails (RoR), HTML, CSS, JavaScript, Mailchimp, Postmark, SendGrid, Full-stack, Full-stack Development, Back-end, API Integration, REST API Clients

Lead Software Developer

2021 - 2023
AIIR Consulting
  • Led a software development team across three continents and time zones. Designed a system architecture for a coaching platform with Fortune 500 companies. Used NextJS, RoR, PGSQL, Redis, Sidekiq, AWS ECS, and AWS EB.
  • Led software development for a stress management iOS App using Swift, Ruby on Rails, PostgreSQL, Contentful, and AWS EB.
  • Integrated Metabase as a dashboard and reporting system for the whole company. Embedded it into the main coaching app.
  • Created a Hubspot integration allowing the coaching platform to display contract information. Created custom Hubspot cards that displayed engagement information in Hubspot from the coaching platform.
  • Created Qualtrics surveys integration, allowing the coaching platform to trigger Qualtrics surveys based on events.
Technologies: Ruby on Rails (RoR), Ruby, Sidekiq, Amazon Elastic Container Service (Amazon ECS), PostgreSQL, React, Next.js, HubSpot, HubSpot CRM, Qualtrics, Node.js, Technical Leadership, TypeScript, Software Architecture, Solution Architecture, Full-stack, Proof of Concept (POC), Full-stack Development, Metabase, Technical Architecture, Architecture, Back-end, Tailwind CSS, WhatsApp, API Integration, REST API Clients

Full-stack Developer

2020 - 2021
MYRM Technologies, LLC
  • Designed system architecture for a finance platform built to replace Salesforce.
  • Led the front and back-end teams located in two different time zones.
  • Created custom data migration tools from Salesforce files.
Technologies: React, Ruby on Rails (RoR), Redshift, PostgreSQL, Salesforce, Heroku, Full-stack, Full-stack Development, Back-end, API Integration, REST API Clients

Web App Architect

2020 - 2020
Colorado General Assembly
  • Created the architecture for the new Colorado General Assembly website, consisting of an admin site, public API, search API, background workers, and a React site.
  • Created an importer into Legacy for their old Drupal app, using a REST client and scheduled Sidekiq workers.
  • Drafted documentation for the architecture and weekly estimations.
Technologies: Sidekiq, PostgreSQL, Elasticsearch, React, Ruby on Rails (RoR), CTO, Full-stack, Proof of Concept (POC), Full-stack Development, Software Architecture, Solution Architecture, Metabase, Technical Architecture, Architecture, Back-end

Senior Rails Developer

2020 - 2020
Booster Apps
  • Created a multi-channel abandoned cart recovery app built on Ruby on Rails 6, using Shopify API, PostgreSQL, Sidekiq, Facebook API, Twilio API, and Mailgun. This app was installed by thousands of merchants and generated $200,000,000 in revenue.
  • Implemented Twilio API to send SMS and WhatsApp messages.
  • Integrated the Facebook Messenger API to send messages with discounts and checkout links.
  • Executed the Mailgun API to send discounts and checkout links.
  • Integrated with the Shopify API to get abandoned carts sessions.
Technologies: Mailgun, Twilio API, Facebook API, Shopify API, Ruby on Rails (RoR), Full-stack, Full-stack Development, Back-end

Back-end Engineer

2019 - 2020
  • Created the MVP for a new platform connecting brands with Airbnb hosts using Ruby on Rails, React, ElasticSearch, and PostgreSQL.
  • Retrieved data from Airbnb listings parsing the HTML response and extracting information from tags and JSON data.
  • Implemented Facebook and Google authentication using OmniAuth.
  • Implemented the SendGrid API using templates for transactional emails.
  • Created a model for storing images—with original, mid, and thumbnails resolution—uploading all versions to AWS S3.
  • Created an AWS infrastructure, setting up EC2, RDS, S3 and loading balancers. Set up SSL configuration, Nginx, and Unicorn.
Technologies: Amazon Web Services (AWS), GitHub, MySQL, Ruby on Rails (RoR), Ruby, Contentful, Heroku, Proof of Concept (POC), Back-end

Lead Developer

2018 - 2018
  • Created a Ruby on Rails 4 web app for order analysis and detecting anomalies, implementing Devise for user authentication.
  • Created the Excel file import process using AXLSX gem, building customer statistics, and exporting them to PDF using PDKit.
  • Generated reports, using Axlsx, in CSV format to show the order analysis, anomalies, and confidence rate.
Technologies: SendGrid, Microsoft Excel, MySQL, Ruby on Rails (RoR), Ruby, Full-stack Development, Full-stack, Software Architecture, Solution Architecture, Metabase, Technical Architecture, Technical Leadership, Architecture, Back-end

Lead Developer

2015 - 2018
Email Delivered
  • Built the CSV contact importer process supporting CSV files with over 2 million rows.
  • Developed the contact search engine, supporting millions of documents.
  • Created an AB testing email engine, supporting automatic AB testing and winner selection.
  • Built the smart marketing campaign engine, supporting dynamic campaign flow and timed delayed campaigns.
  • Developed smart list segmentation, creating dynamic lists based on custom properties (field values, engagement history, tags, custom fields).
Technologies: Amazon Web Services (AWS), Bootstrap, Redis, MySQL, Elasticsearch, Ruby on Rails (RoR), Ruby, Full-stack Development, Full-stack, Software Architecture, Solution Architecture, Metabase, Technical Architecture, Technical Leadership, Architecture, Back-end

Senior Software Engineer

2013 - 2015
  • Created a Ruby gem that reads user-generated content from Facebook pages and inserts them into a proprietary API.
  • Developed a Ruby on Rails website to manage and map Facebook pages to user accounts.
  • Built a Ruby gem that listens to tweets in real time and inserts them into a proprietary API.
  • Programmed a Ruby gem that reads comments from Disqus and inserts them into a proprietary API and, after they are processed, posts moderation results back to Disqus.
  • Wrote a Ruby on Rails website for Facebook Page Insights.
  • Created a Ruby gem that reads sitemaps and looks for Facebook comment boxes and imports their comments into a proprietary API.
Technologies: Bootstrap, jQuery, Redis, MongoDB, ActiveMQ, Ruby on Rails (RoR), Ruby

Software Developer

2012 - 2013
DC Group Argentina
  • Maintained the DescuentoCity website written in Ruby on Rails.
  • Created a mailer process to send a custom newsletter to 300+ thousand users using Amazon SQS and multiple AWS workers.
  • Integrated Facebook into the website, allowing users to like and comment on each deal, using Facebook JavaScript SDK.
  • Built an administration website using Ruby on Rails, Bootstrap, jQuery, and MySQL.
  • Coded a deal-sorting algorithm based on user views/clicks.
Technologies: Amazon Web Services (AWS), jQuery, MySQL, Ruby on Rails (RoR)

Software Developer

2012 - 2013
  • Created an Entity Framework extension to generate classes based on a stored procedures result.
  • Maintained an ASP MVC online platform for managing television ad placement.
  • Implemented a search engine library in a services marketplace site.
  • Created a mobile-based website for wine store order processing.
  • Created an MVC website to compare real estate property prices based on multiple factors.
Technologies: JavaScript, jQuery, Bootstrap, Microsoft SQL Server, .NET, C#

Software Developer

2011 - 2012
  • Created a business intelligence web panel for online Facebook games.
  • Built a custom reports platform where users were able to share their reports with other users.
  • Wrote a batch process to move and compact SQL server table information to archive tables.
  • Developed an online dashboard that aggregates multiple game information.
  • Programmed a tool to import users' friend lists from the Facebook API and generate a custom report to analyze game acquisition virality.
Technologies: jQuery UI, jQuery, Web MVC, Microsoft SQL Server, C#

Software Developer

2008 - 2010
  • Implemented AFIP (government) web services in an invoice system.
  • Modernized the system UI, adding new DevExpress .NET components.
  • Maintained SQL stored procedures.
  • Created a custom reporting tool in C# using DevExpress components.
  • Implemented an LA POS (credit card) payment system in the invoicing system.
Technologies: Microsoft SQL Server, C#, .NET

Coachingzone: A Coaching Platform for a Company That Serves Fortune 500 Clients
A Ruby on Rails and React coaching platform. As the lead developer, I managed three teams across multiple continents, designing the architecture and the infrastructure. The application helped various types of users, such as HR roles, coaches, coachees, account managers, and administrators.

Showplace HQ
A platform that connects brands with Airbnb super hosts built on Ruby on Rails and React. It allows brands to create their campaigns and give away products to Airbnb hosts for free in exchange for content creation and other custom requirements.

Shopify Abandoned Cart Recovery Tool

A Ruby on Rails web app for merchants that allows users to recover abandoned cart sessions by letting them subscribe with an opt-in popup using different channels like SMS, Whatsapp, Email, Facebook Messenger, and push notifications.
2010 - 2014

Bachelor's Degree in Computer Engineering

Universidad Abierta Interamericana - Buenos Aires, Argentina


Facebook API, HTML Offline API, jQuery, React, Ruby on Rails API, Shopify API, Twilio API, Sidekiq, SendGrid API, X (formerly Twitter) API, Mongoid, jQuery UI, Node.js, WhatsApp API, OpenAI Assistants API, Inertia


ChatGPT, Sublime Text, Git, Microsoft Excel, GitHub, Mailchimp, ActiveMQ, Capistrano, NGINX, SendGrid, Terminal, Amazon Elastic Container Service (Amazon ECS), Qualtrics, RSpec


Ruby on Rails (RoR), ASP.NET MVC 5, OAuth 2, Bootstrap 3, Sinatra, AngularJS, Ember.js, Tailwind CSS, Bootstrap, Ruby on Rails 5, .NET, Chrome, Next.js, NestJS, Svelte, Capybara, Redux


JavaScript, SQL, HTML, Ruby, Unicorn, T-SQL (Transact-SQL), C#, CSS, GraphQL, TypeScript, Python




Heroku, Docker, MacOS, Ubuntu, Mailgun, Amazon EC2, Twilio, Amazon Web Services (AWS), Visual Studio Code (VS Code), Contentful, Salesforce, HubSpot


Elasticsearch, PostgreSQL, Databases, Microsoft SQL Server, MySQL, Amazon S3 (AWS S3), Redis, NoSQL, MongoDB, Redshift


Back-end, Proof of Concept (POC), Full-stack Development, WhatsApp, API Integration, REST API Clients, Technical Leadership, Technical Architecture, Architecture, CTO, Metabase, Software Architecture, Solution Architecture, Full-stack, OpenAI GPT-3 API, Chatbots, OpenAI, APIs, ChatGPT API, Web Servers, Web MVC, Amazon Route 53, Computer Engineering, Postmark, HubSpot CRM, OpenAI GPT-4 API, Large Language Models (LLMs), reCAPTCHA

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