Hello 👋

I'm Alex O'Callaghan and this is my personal website where I write about software development and do my best to learn in public. I currently work at Mintel as a Principal Engineer working primarily with React, TypeScript & Python.

I've been leading one of our platform teams, first as an Engineering Manager and now as a Principal Engineer, maintaining a collection of shared libraries, services and a micro-frontend architecture.


Recent posts

Using the experimental React Compiler

Published

Trying out the React Compiler with React 19 beta

Using GitLab API to create a DORA metrics dashboard

Published

Measure developer team productivity using deployment frequency and lead time for changes

Using TypedDict with invalid attribute names

Published

How to use a TypedDict with item keys that aren't valid identifiers

Mock server-sent events (SSE) with msw

Published

Mock Service Worker supports mocking SSE

Exclude node_modules with Webpack

Published

Avoid bundling dependencies when building a library

Accessibility testing

Published

Overview of approaches and tools for testing web accessibility

Dynamically load remoteEntry.js files

Published

Control loading Webpack Module Federation remoteEntry.js files to improve peformance

Configure Boto3 endpoint_url

Published

Use environment variables to point Boto3 at local services

Mocking Boto3 with pytest

Published

Mock requests to AWS services with pytest

Platform team challenges

Published

Challenges faced when introducing a platform team

Python TypedDict with Generics

Published

How to define a Python type for a dict with generic values

Contract testing with OpenAPI & TypeScript

Published

Validate contracts between backend services and frontend applications

Design system management

Published

Processes and challenges in managing an adopted design system

Adopting a micro-frontend architecture

Published

Supporting scaleable web application development with micro-frontends