Efren Macasaet

Senior Full Stack Developer - Connecting User-friendly Interfaces with Data and Analytics · Vancouver, Canada · efren@iwoork.com

As an accomplished full-stack developer, I offer more than ten years of extensive experience in software development, specializing in React JS, Next JS, GraphQL (or APIs), and AWS technologies. My primary focus is producing clean and exceptionally efficient code, with an unwavering commitment to improving its quality. I approach my work by placing a premium on simplicity in user interfaces, guided by a profound understanding of human interactions.

Drawing from my wealth of experience, my dedication lies in delivering streamlined, user-centric solutions. Furthermore, I possess a background in designing and recording data from user interfaces and integrating it with critical data sources, facilitating the generation of valuable business insights.

Furthermore, I bring prior experience in product development to the table, which aids me in identifying the features necessary to address customer pain points. The synergy of this experience with my engineering skills empowers me to construct and prioritize features that deliver a delightful user experience.


Engineering Lead

December 2021 - September 2023
  • Architected and constructed an end-to-end experimentation platform using Next JS and integrated it with third-party platforms (Airtable, Streamlit, Launch Darkly, etc.).
  • Developed an SDK for the experimentation platform to maintain consistency across teams.
  • Conducted investigations into application issues through the execution of SQL queries on the data.
  • Facilitated architecture discussions to address common and recurring problems across teams. This enabled the design of a system that not only tackles one use case but also addresses multiple pain points.
  • Oversaw the recruitment and direct management of 12 engineers.
  • Created a self-service schema management platform to ensure uniformity in data collection. Collaborated on CSS enhancements to improve the user experience.
  • Established a campaign management system that allows stakeholders to independently manage campaigns and tags. This resulted in improved HTML page scores and SEO rankings, as tags are no longer loaded when campaigns have concluded.
  • Led the initiative to transition third-party tracking to the server side, employing Server-side Google Tag Manager and Google Cloud Platform. This lead to a match rate of users from 95.9% to 99.9%

Senior Technical Product Manager - Marketing Data Engineering

Expedia Group
November 2020 - December 2021
  • Conceptualized and constructed the marketing data platform for ingesting data from TV platforms through CSV imports.
  • Led the migration of Facebook and Google Ads tracking from the client-side to the server-side.
  • Conducted investigations into application issues by executing SQL queries on the data.

Technical Product Manager, Data Platform (attribution)

Expedia Group
August 2019 - November 2020
  • Developed an attribution platform that caters to multiple attribution use cases. Previously, attribution was confined to a single model, but the platform my team created empowers the business to examine the data using various models.
  • Conducted investigations into application issues by executing SQL queries on the data.

Global (Technical) Product Manager

Brand Expedia - Expedia Group
June 2017 - August 2019
  • Developed Expedia's inaugural end-to-end experimentation platform, which proved instrumental in fostering an inner-source culture within the company. The application gained significant traction and saw widespread use across the organization.
  • Employed RESTHeart for the API, utilized MongoDB for the database, and implemented React JS for the front end, all while hosting the application on Azure.

Senior Product Analyst, Mobile Apps

Hotels.com - Expedia Group
March 2016 - June 2017
  • Led the integration of a third-party platform (Crittercism/Apteligent) for measuring the speed performance of mobile apps.
  • Constructed a performance dashboard using Tableau.
  • Enhanced the application's page speed by reducing the size and number of API requests, resulting in a million-dollar increase in revenue.
  • Conducted investigations into application issues by executing SQL queries on the data.

Senior Product and Site Optimization Analyst, APAC

Hotels.com - Expedia Group
July 2014 - March 2016
  • Led the implementation of voice search for users in China, Japan, Taiwan, and Korea, resulting in increased conversion rates in these markets.
  • Worked in collaboration with the search team to enhance tokenizers tailored to the China, Japan, Taiwan, and Korea markets, leading to improved click-through rates.
  • Developed a company-wide dashboard using Tableau to oversee overall conversion metrics.
  • Conducted investigations into application issues by executing SQL queries on the data health specific to the APAC markets.

Product Manager

Live It China Ltd
December 2013 - July 2014
  • Head of product development for LiveItChina.com.
  • Setup a Philippines company and office and hired the entire engineering and UX team

Digital Producer

Alchemy Asia
July 2012 - December 2013
  • Handled website development of clients based in Hong Kong and Australia
  • Developed a platform for connecting brands with influencers

Lead Developer

I Love Ltd
July 2011 - July 2012
  • Conceptualized and developed the ilovehongkong.hk, ilovesoho.hk, ilovelkf.hk brands.
  • Oversaw the recruitment and direct management of engineers

Lead Web Developer

CNN - Turner Broadcasting
November 2009 - July 2011
  • Led the engineering team based in India and UK (CNN Travel)
  • Performance optimization for the CNNGo Drupal site

Web Architect

South China Morning Post
October 2008 - November 2009
  • Initially collaborated with the Classifieds team based in Singapore, later relocating to Hong Kong.
  • Envisioned and spearheaded the development of SCMP's new vertical named "At Your Service," serving as a serviced apartment directory in Hong Kong.

Senior Web Developer

Singapore Press Holdings Ltd
October 2006 - October 2008
  • Oversaw the project of transitioning Hardwarezone.com to an API-based platform powered by Google Mini.
  • Managed the upkeep of the high-traffic Hardwarezone forums.
  • Developed campaign pages for clients, including Canon, Nokia, Samsung, and others.

Founder / Managing Director

Iwoork Web Solutions (closed)
February 2012 - January 2016
  • Overall set up of the business and ownership including P&L management. Grew the company from just me to a team of 7 engineers and UI/UX. The company operated with the business model of providing tech teams to other businesses with focus on continously improving the process to effectively deliver client's needs.


Here are a selection of products that I conceptualized, developed and own:

Coffee Brew Notes

Brew Better Coffee

I built this application to track every shots I pull from my coffee machine. This enables me to save the various configurations of my grinder in relation to my supply of beans. It has the ability to upload images for every shot.

Tech setup:

Next JS, Material UI, AWS Cognito (user management), AWS API Gateway (API), AWS DynamoDB (data store), Serverless Framework for deploying the stack, Automated versioning and deploy via Github Actions


Home buying made simple

A data-driven insights providing strata, location and investment analysis using OpenAI API

Tech setup:

Monorepo, Next JS, Material UI, AWS Cognito (user management), AWS API Gateway (API), AWS DynamoDB (data store), Serverless Framework for deploying the stack, Automated versioning and deploy via Github Actions

Auction Platform

An auction platform with integrated marketplace

Tech setup:

Monorepo, Next JS, Material UI, AWS Cognito for user management, AWS API Gateway for API, AWS DynamoDB for data store, Serverless Framework for deploying the stack, Automated versioning and deploy via Github Actions


  • Javascript
  • Typescript
  • Python
  • PHP
Front End
  • React JS
  • Next JS
  • Material UI
  • Tailwind CSS
  • Express JS
  • Nest JS
  • Amazon API Gateway
  • GraphQL
  • Jest
  • React Testing Library
  • Github Actions
  • Jenkins
  • Linting with ESLint
  • Git hooks with Husky and lint-staged
  • Prettier code formatter
  • Turborepo
  • MongoDB
  • PostgreSQL
  • DynamoDB
  • MySQL
  • Microsoft SQL
  • New Relic
  • Splunk
  • Monte Carlo
  • Amazon CloudWatch
  • Twilio's Segment
  • Snowflake
  • Google Analytics
  • Looker Studio
  • Metabase
  • Presto
  • SQL


I find pleasure in playing music with my Telecaster and Fender Mustang GT40 in the comfort of my own home. My musical taste leans towards indie bands like Death Cab for Cutie, Two Doors Cinema Club, and Crash Captains.

Additionally, I take delight in brewing my own coffee at home and I'm constantly on the lookout for new and interesting coffee beans to experiment with.