Principal Software Engineer — AI-Led Delivery

Defaqto; Farringdon; Hybrid; GBP 110,000 - 140,000; Full time

Job summary

Defaqto is seeking a Principal Software Engineer to be the most senior individual contributor in the Technology function in London. You will own engineering standards, technical direction, and the shift from AI-assisted coding to AI-led delivery, guiding multiple squads with hands-on responsibility and no mandatory people management.

You will shape long-term technical strategy, oversee secure data governance, and ensure tests, static analysis and reviews meet high quality standards.

Qualifications

• Substantial commercial software engineering experience at staff, principal or equivalent level.
• Hands-on in modern stack including .NET/C#, TypeScript, Azure, Python or PHP.

Responsibilities

• Lead the shift from AI-assisted coding to AI-led delivery, with engineers guiding agents and owning outcomes.
• Define high standards for code review, testing, security, and architecture across Defaqto Technology.
• Own architecture decisions that cross team boundaries and document with ADRs.
• Coach squads through technology shifts, raising the bar for quality and accountability.

Skills

Staff level

Software architecture

AI-led delivery

Tools

.NET

C#

TypeScript

Azure

Python

PHP

SQL

Job description

Defaqto is seeking a Principal Software Engineer to be the most senior individual contributor in the Technology function in London. You will own engineering standards, technical direction, and the shift from AI-assisted coding to AI-led delivery, guiding multiple squads with hands-on responsibility and no mandatory people management.

You will shape long-term technical strategy, oversee secure data governance, and ensure tests, static analysis and reviews meet high quality standards.