About
Hello, I'm Mira.
I started out writing PHP for a local newspaper and have since worked in fintech, healthcare and developer tooling, at companies from four people to four thousand.
These days I work independently with a small number of clients at a time. Most engagements involve a system that has to be dependable: money moving between accounts, patients booking appointments, researchers trusting their data.
I care about clear writing as much as clear code. Every engagement ends with documentation, a recorded walkthrough and a team that is confident running what we built together.
Outside work I maintain a couple of small open-source tools, mentor career changers through a local bootcamp and spend too much time cycling up hills around Bristol.

Experience
Where I've worked
2022 to now
Independent software engineer
Mira Castell Engineering Ltd
Product, platform and audit engagements for fintech, healthcare and SaaS teams.
2018 to 2022
Staff engineer
Northgate Labs
Led the payments platform team and introduced the company's design-review process.
2015 to 2018
Senior engineer
Kestrel Insurance
Moved the quote engine from a monolith to services and built the internal developer portal.
2013 to 2015
Web developer
Avon Courier Digital
Built the newsroom's publishing tools and the paper's first responsive website.
Toolbox
What I work with
Tools change; the habits behind them don't. These are the ones I reach for most often.
Languages
Front end
Back end and data
Infrastructure
Principles
How I work
- 01
Small, reversible steps
Feature flags, shadow modes and gradual roll-outs. Big-bang releases are where projects go to die.
- 02
Write it down
Design notes, decision records and runbooks are part of the work, not an afterthought.
- 03
Measure first
Performance, reliability and cost are measured before they're optimised.
- 04
Leave a team behind
Success is your engineers owning the system confidently after I've gone.