Available for interesting problems

Janzen Zarzoso

Senior Software Engineer

15+ years across the stack•Wellington, New Zealand

About

Building software, end to end

I'm a Senior Software Engineer with 15+ years of experience across the full stack — from front-end product work to back-end services, infrastructure, and the delivery practices that hold teams together. I've built customer-facing features used by businesses worldwide, led front-end modernisation efforts, and worked deep in the platform layer designing APIs, CI/CD pipelines, and deployment architecture.

Currently at Xero, I split my time between hands-on engineering and the surrounding craft: mentoring engineers, writing the documentation and frameworks that make delivery predictable, and exploring how AI-assisted workflows can make teams faster without cutting corners. I care about software that's reliable, teams that compound their improvements over time, and practices that outlast the person who introduced them.

Before Xero, I worked across agencies and remote teams in New Zealand, Australia, the US, and the Philippines — shipping everything from e-learning platforms to POS systems to CMS tooling, and picking up AWS, DevOps, and full-stack JavaScript along the way.

Experience

Where I've worked

Senior Software Engineer

Jan 2020 – Present
Xero · Wellington, New Zealand
  • Developed the Invoicing API and Sales Summary API from setup to production, migrating existing consumers onto a platform that now sustains 2,000 requests per minute.
  • Shipped a feature on a critical endpoint of the public Accounting API, serving over 1 billion requests per month.
  • Led the micro front-end migration of the New Invoicing front-end, owning planning, estimation, and risk assessment through to production rollout.
  • Cut GitHub workflow processing time by 77% through targeted CI/CD improvements, then propagated the patterns across adjacent teams.
  • Spearheaded shareable AI agent skills and reusable workflows adopted team-wide, improving API readiness for AI-assisted use to a 95%+ compliance score.
  • Established the team's Delivery Lead Time review framework, authored ADRs and onboarding docs, and mentored engineers across the team and beyond.

Software Developer

Aug 2017 – Jan 2020
Springload · Wellington, New Zealand
  • Built front-end and back-end solutions with React, Django, and Node.js for cross-functional teams on multi-award-winning projects.
  • Owned feature planning, estimation, and delivery using Agile practices; contributed to code reviews, open-source projects, and security upgrades.
  • Applied accessibility (a11y), web usability, and BEM standards across client projects.

Full Stack JavaScript Engineer / DevOps Engineer

Apr 2016 – Jul 2017
D3FY Development Group · Phoenix, Arizona (Remote)
  • Lead developer on most projects for a fully remote US–Philippines team, contributing to decision-making, estimation, and developer training.
  • Managed CI/CD pipelines with Ansible, Vagrant, and AWS; built a versioned backup solution for files and databases using S3.

Earlier: Full Stack Web Developer at ShareSource (Philippines) and jDynamic (Australia); Senior Web Developer at C5Extras (Australia); Software Design Engineer at NEC Telecom Software Philippines — where I helped build automation tooling that lifted productivity 60% and quality 400%, won the 2012 Presidential Award, and contributed to a CMMI Level 3 certification.

Skills

Tools of the trade

Languages

  • C# / .NET
  • JavaScript
  • TypeScript
  • Java
  • Python
  • PHP
  • HTML & CSS

Frontend

  • React
  • Micro Front-ends

Backend

  • .NET
  • Microservices
  • REST APIs
  • Node.js
  • Django

Infrastructure & DevOps

  • Kubernetes
  • EKS
  • GitHub Actions
  • TeamCity
  • Octopus
  • Helm
  • Terraform
  • AWS
  • Docker

AI & Automation

  • Claude
  • GitHub Copilot
  • Prompt Engineering
  • AI-assisted Development
  • Agent Workflows

Practices

  • SLOs / SLIs
  • Observability
  • Resiliency
  • Agile / Scrum
  • Design Review
  • Automated Testing
Certifications

Credentials

AWS Certified Solutions Architect

Associate (SAA-C03)

AWS Certified Developer

Associate (DVA-C02)

AWS Certified Cloud Practitioner

CLF-C02

Sumo Logic Certified

Search Mastery

Sumo Logic Certified

Fundamentals

Education: Ateneo de Davao University, 2004–2009 — Dean's Lister

Beyond Code

When I'm not shipping

☕

Coffee

I take my coffee making seriously — dialing in grind, ratios, and brew methods is its own kind of debugging.

🥐

Baking & Cooking

Baking and cooking are where I slow down — precise, hands-on, and a good counterbalance to a day of code.

🎮

Back to Life NZ

My side business modifying video game controllers and repairing consoles back to life.

@back.to.lifenz on Instagram