Senior Engineer - Full Stack

Our mission at what3words is to become the global standard for addressing. Street addresses weren’t designed for 2025. They aren’t accurate enough to specify building entrances, and they don’t exist for parks, rural areas and many parts of the world. This makes it hard to find places and causes problems and inefficiencies on a global scale.

That’s why we created what3words. We divided the world into 3m squares and gave each square a unique combination of three words. It’s the easiest way to find and share precise locations.

In late 2024, we welcomed Swiftcomplete into the what3words family. Their expertise in fast, intelligent, and scalable address validation technology strengthens our ability to make location data even more accessible, accurate, and easy to use. Together, we’re building the most powerful addressing standard and address validation products in the world.

Over the last year, what3words has been used in 193 countries, and our monthly active users continue to grow at an impressive pace. Our tech is used by emergency services, delivery companies, eCommerce businesses, ride-hailing apps and NGOs, and is integrated into the navigation systems of millions of cars around the world.

The Role

We are looking for a Senior Full Stack Engineer to develop an address autocomplete & validation app for Shopify, focusing on Checkout UI Extensions and app Admin configuration. This is a supported role with mentoring. Work closely with Swiftcomplete Product Managers—who define scope & functionality—and collaborate in the design process based on your experience.

Collaboration with Product Management

You’ll work closely with Swiftcomplete Product Managers who own scope and business outcomes. They will collaborate with you in the design process and expect you to contribute options and trade‑offs based on your engineering experience.

Responsibilities

• Build the address autocomplete & validation app aligned with Shopify’s latest extensibility patterns.Implement Checkout UI Extensions in React + TypeScript for merchant UX at checkout.
• Build an embedded Admin/Settings experience using App Bridge + Polaris.
• Develop and maintain Node.js/TypeScript endpoints that integrate with Swiftcomplete APIs securely.
• Contribute to/Own (role dependent) Shopify Functions in Rust for validation logic.
• Use Shopify CLI to scaffold, preview, deploy, and release extensions/functions.
• Write maintainable code, contribute to code reviews, and improve reliability and performance.

Required Skills

• React, TypeScript, Rust, Node.js
• Familiarity with Shopify‑specific constraints and components, including Functions, App Bridge, Polaris
• Familiarity with Shopify CLI (scaffold, preview, deploy/release)

Nice‑to‑Have Skills

• Familiarity with Liquid + Theme App Extensions
• Address/geocoding domain knowledge
• Interest in MCP & AI agent integrations

Required Experience

• 3–5 years engineering experience
• Shipped at least one Shopify app or extension (Checkout or Customer Account preferred)
• Implemented webhooks with HMAC; integrated 3rd‑party APIs
• Comfortable with Shopify CLI and GraphQL basics
  

The role is based in our centrally located HCMC office. While you can work from the office five days a week if preferred, our Engineering team can choose to work up to two days a week from home. We also offer a six-week remote-work allowance; for up to six weeks a year, you can work from anywhere in the world (as long as you’ve got great WiFi and are happy to work with your main office timezone).

Equality, diversity and inclusion at what3words

Our mission is to help everyone talk about everywhere, and we believe diverse perspectives make for a better company and better products too. We strongly encourage applications from underrepresented groups and are committed to diversity, equity and inclusion in our hiring processes and company culture.

Benefits

We offer the following benefits to all permanent employees of what3words:

• Flexible working
  
• Competitive salary
  
• 6 week remote working (work from anywhere) policy
  
• 25 days holiday: plus the option to buy more!
  
• Share options
  
• Private health insurance
  
• Wellbeing Days
  
• Generous parental leave policies
  
• Family friendly policies
  
• Lunch & learn sessions
  
• Team social budget