Principal Software Engineer (.NET/Umbraco or PHP/Drupal)

In this Principal Engineer role you provide technical leadership across Manifesto’s client estate, shaping architecture and solving critical live issues. You work across multiple platforms and languages, ensuring maintainable, simple designs while guiding complex projects. You’ll operate at senior levels with clients and internal teams, driving high-impact technical decisions that align with budgets and long-term maintenance. This role offers the opportunity to influence a broad surface, mentor engineers, and stay current with evolving tools and practices, including AI-assisted engineering.

• Provide technical authority across client estates, spanning platforms, hosting environments, and codebases.
• Shape technical solutions for new business from qualification through discovery to estimation.
• Lead architecture on the largest and most complex client projects.
• Act as senior escalation point for live incidents and complex problems across stacks.
• Raise engineering standards through mentorship, reviews, and clear standards.
• Represent Manifesto credibly with senior technical stakeholders.

• Cross-stack technical depth across .NET/Umbraco and PHP/Drupal
• Architectural leadership for robust, scalable, secure systems
• Cloud and infrastructure experience with Azure and CI/CD, IaC
• Diagnostic ability under pressure to quickly understand unfamiliar codebases
• Technical discovery including qualification, solution design, and estimation
• Software engineering fundamentals, security, testing, accessibility
• Leadership and mentorship of engineers; commercial awareness and stakeholder communication
• Strong communication to non-technical stakeholders and client confidence

• calm under pressure and clear communication
• pragmatic problem-solving with simplicity in mind
• proactive long-term technical direction alignment with business goals
• Umbraco and .NET stack
• Drupal and PHP stack
• Azure cloud, CI/CD pipelines, infrastructure as code