Humberto Contreras

About

I'm a backend engineer — 20+ years of it spent on systems that had to stay up in production: a reverse auction where the lowest unique bid wins, an e-invoicing platform, a mobile marketplace, SMS services sitting in front of national carriers.

I've worked across telecom, fintech, banking, e-commerce and media: as a co-founder inside a Mexican technology group, as a senior engineer at an international product consultancy, and remotely with teams in the U.S. and Europe. Node.js and MongoDB are home now; PHP and MySQL came first.

The numbers I care about are other people's: 820,000 active users on a platform I architected, a million subscribers on a marketplace I helped run, and $120–150K a day moving through it at its peak.

Projects

Quién Paga Menos — auction listing page showing three finished iPad and iPhone auctions with their winning bids.

Quién Paga Menos

Reverse auction platform · own product

A reverse auction where the lowest unique bid wins. Nobody races to bid highest: users buy credits and compete to place the single lowest bid that no one else matches, watching a live Top 10 leaderboard while instant notifications tell them the moment they are knocked out.

It began as a real-time reverse auction platform for a mobile network operator in Haiti, where subscribers bid credits on prizes like an iPad, Apple Watch or MacBook. That system grew into a standalone product, rebuilt around Node.js, MongoDB and WebSockets to handle bid submission, leaderboard updates and notifications as they happen.

  • A real-time bid engine over WebSockets — submissions, instant notifications and a live Top 10 leaderboard.
  • Credit-based bidding, so every bid is a paid, traceable transaction rather than a free click.
  • Built first for a mobile operator, then re-architected as a product of its own with its own accounts and auctions.
  • Node.js
  • MongoDB
  • WebSockets
  • Real-time

I'm writing up more of these. The résumé above covers the rest.

Skills

Backend

  • Node.js
  • REST APIs
  • WebSockets
  • GraphQL

Languages

  • JavaScript
  • TypeScript
  • PHP
  • SQL

Databases

  • MongoDB
  • MySQL
  • MS-SQL
  • Redis
  • ArangoDB
  • SQLite

Cloud & Infrastructure

  • AWS
  • Docker
  • Linux
  • Nginx
  • Apache
  • CI/CD
  • Git

Practices

  • Authentication & authorization
  • Real-time systems
  • Database design
  • API integration
  • Technical leadership

Education

Software Engineer

Universidad Autónoma de Nuevo León

Languages

  • Spanish Native
  • English Advanced

Contact

I'm based in Monterrey, México, and I work remotely with teams anywhere. Email is the fastest way to reach me — whether it's a role, a system that needs untangling, or just a question.

Say hello