Portfolio

William Montiel

Senior Software Engineer

Software Engineer with 12+ years of experience engineering high-scale, real-time systems. My trajectory spans from co-building a mass email marketing SaaS from scratch in a 3-person team, to architecting cloud-native telemetry platforms and leading international engineering teams on-site in Vietnam. Specializing in logistics, GPS tracking, and full-stack mobile ecosystems, I bridge complex backend architectures with effortless user experiences. My focus is simple: taking complete technical ownership, setting architectural standards, and stripping away complexity to build software that scales.

Experience

Dec 2024 — Present
Software Developer Engineer III
Zonar Systems
  • Team Leadership & Global Collaboration Spearheaded the mobile development division, leading an international engineering team on-site in Vietnam (Ho Chi Minh City) to align cross-border product delivery, optimize codebase performance, and streamline development workflows.
  • Full-Stack Engineering Developed an end-to-end dynamic forms feature following established architectural guidelines, building a drag-and-drop web builder in React and a dynamic rendering module for the GPS Trackit Driver app using React Native. Backend powered by GraphQL APIs on AWS Lambda, utilizing MySQL for core data and MongoDB for flexible schemas.
Mar 2021 — Dec 2024
Senior Software Engineer
TSO Mobile / GPS Trackit
  • Recruited Back Brought back by a former manager into an expanded role. With Platform Manager matured and handed off to another team, I helped kick off the company's next flagship product.
  • GPS Trackit Cloud Co-built GPS Trackit Cloud, the large-scale platform our customers use to run their fleets — real-time vehicle tracking on the map, live camera streaming, alerts, driver-behavior monitoring, fuel-consumption insights, and reporting.
  • Full-Stack at Scale Delivered across a broad stack: React on the front end, AWS Lambda, MySQL and MongoDB.
Oct 2020 — Mar 2021
Senior Software Engineer
Fullstack Labs
  • Geospatial Tooling Designed and developed a high-precision roof measurement tool from scratch using Vanilla JavaScript and the Google Maps API for a major drainage infrastructure enterprise, automating immediate client cost estimations and quoting.
  • E-commerce Migration Executed codebase refactoring and migration strategies for high-traffic platforms like Fulton Fish Market (NYC), transitioning legacy PHP architectures into optimized, modern systems.
Sep 2018 — Oct 2020
JavaScript Developer
TSO Mobile / GPS Trackit
  • Front-End Engineering Developed front-end features for the company's real-time GPS and geolocation platform using Ember.js.
  • Legacy Systems Moved into a legacy area of the product built on C# and Microsoft SQL Server, maintaining and extending long-standing systems.
  • Greenfield Platform Co-built "Platform Manager" from scratch with another engineer — the internal system for administering the GPS trackers and cameras the company installs in customer vehicles. Built on early React with AWS Lambda backend and MySQL.
Apr 2017 — Aug 2018
Web Developer
Vectorial
  • Enterprise Platforms Built and maintained a multi-tenant corporate employee performance review and appraisal platform using Ruby on Rails, Angular, and MySQL.
  • Agile Delivery Delivered customized software architectures tailored to diverse client specifications in a fast-paced agency environment.
Jul 2015 — Feb 2017
Web Project Leader & Developer
Sigma Móvil SAS
  • Architecture & Leadership Architected and led a team of 4 developers in building a proprietary All-In-One (AIO) Email and SMS marketing platform from scratch, which remains in active production today.
  • Full-Stack Development Engineered the platform using PHP (Phalcon), Angular, and MySQL, featuring a custom drag-and-drop email builder with pre-designed templates and dynamic contact list management.
  • Workflow Automation Designed an automated multi-channel marketing engine, allowing users to create conditional campaigns (e.g., triggering follow-up emails and SMS based on open rates and user behavior).
  • Analytics & Tracking Implemented a real-time analytics dashboard to track campaign performance, delivery rates, open rates, and spam metrics.
Jul 2013 — Jul 2015
Junior Software Developer
Sigma Móvil SAS
  • Product From Scratch Co-built a mass email marketing SaaS platform as one of the two core junior developers on a 3-person team, scaling the product from inception to commercial viability.
  • Monolithic Architecture Developed a unified full-stack application using Phalcon PHP, Ember.js, and MySQL.
  • Feature Engineering Designed and coded a complex drag-and-drop email template editor and an optimized contact-ingestion pipeline integrated with high-volume MTAs for massive email deployment.

Independent Projects

A few of my largest independent builds. There are more, but these are the ones that mean the most to me.

Transportes Ejecutivos
Ecosystem

A B2B company offering corporate transportation services — and one that runs its entire operation on the platform I built and still maintain. From the web dashboard the team creates and dispatches services with their passengers and pickup addresses, administers passenger, vehicle, and driver records, and automatically flags when a vehicle's or driver's documentation falls out of date, all backed by reporting. I also built a REST API for third-party integrations, a native Android app for drivers, and a React Native app for passengers.

D Side
Internal Operations Platform

Developed an internal task management and operational traffic platform using Laravel (PHP) and Vue.js. Engineered a custom budget estimator tool embedded with complex pricing formulas to optimize client billing accuracy and increase profitability.

Technologies

AI-Assisted Workflow

I build with AI in the loop as a force multiplier — Claude, GitHub Copilot, and Gemini (Google Antigravity) — to prototype faster, review my own code, and keep raising the quality bar. The architecture and the decisions stay mine; the tooling just lets me move quicker and ship better.

Education

2015 — 2019
Systems Engineer
Corporación Universitaria Centro Superior
2009 — 2012
Associate Degree in Computer Science
Universidad Autónoma de Occidente