Principal Software Engineer (Remote)

Salary: £67,000 - 107,000 per year

Requirements:

• Were looking for cross-stack expertise across .NET and Umbraco, as well as PHP and Drupal.
• You bring expert architectural experience designing robust, scalable and secure content-managed platforms, integrations and modern web applications.
• You have practical cloud engineering experience, particularly with Azure, including CI/CD pipelines, infrastructure as code and environment management.
• You have experience with managed hosting platforms such as Azure, Acquia, Umbraco Cloud, WP Engine or Pantheon.
• You have proven ability to diagnose unfamiliar codebases quickly and lead resolution under pressure.
• You have experience qualifying opportunities, conducting technical discovery, producing solution designs and estimating work before sale.
• You demonstrate mastery of clean code, testing, design patterns, security and accessibility standards.
• You have experience developing lead and senior engineers and raising standards through mentorship.
• You understand the commercial implications of technical decisions, including margin, risk and maintenance.
• You communicate complex technical concepts clearly to non-technical stakeholders and build client confidence in difficult situations.
• You have experience with API design and integration, including REST, GraphQL and third-party CRM, payment and marketing platforms.
• You understand security by design and DevSecOps, particularly in relation to supporter and donor data.
• You understand accessibility standards and practice, including WCAG 2.2 and above.
• You have experience with version control, branching strategy and release management across multiple codebases, as well as agile delivery in a client services context.
• Desirable experience includes headless and decoupled CMS architecture; OAuth and single sign-on; search implementation, including AI-assisted or hybrid search; AI-assisted engineering tools and workflows; and work in the charity, non-profit or membership sector.
• You are pragmatic, calm under pressure, proactive in setting technical direction, and committed to developing others and maintaining high standards for quality, reliability, security and maintainability.
• You can move between client contexts, engage confidently with stakeholders, reconcile differing requirements, and identify technologies and approaches that deliver genuine value.

Responsibilities:

• Provide technical authority across our client estate, including multiple platforms, hosting environments and codebases.
• Shape technical solutions for new business, from initial qualification and discovery through solution design and estimation.
• Lead architecture for our largest and most complex client projects, ensuring solutions fit clients budgets, teams and long-term maintenance capabilities.
• Set and uphold technical direction, software design principles and engineering standards, promoting simplicity and maintainable solutions.
• Make hosting, infrastructure and platform decisions with consideration for cost, security and post-launch ownership.
• Serve as the senior technical escalation point across our estate, diagnosing complex problems in unfamiliar codebases and leading responses to significant incidents.
• Establish root causes, direct remediation, communicate clearly during incidents and drive changes to prevent recurring problems.
• Raise engineering standards through technical reviews, governance, software development lifecycle practices and constructive challenge of ineffective approaches.
• Mentor and develop lead and senior engineers, share knowledge and create opportunities for others to grow.
• Keep current with tools, standards and trends, including AI-assisted engineering practice.
• Support our marketing and new business work through prototypes, thought leadership or presentations where appropriate.

Technologies:

• AI
• API
• Azure
• CI/CD
• Cloud
• CMS
• CRM
• DevSecOps
• Drupal
• Embedded
• GraphQL
• Support
• Marketing
• OAuth
• PHP
• REST
• Security
• Umbraco
• Web
• ASP.NET

More:

We are Manifesto, a digital experience agency for changemakers, creating purposeful, ethical, inclusive, accessible and sustainable digital experiences, products and services. Our clients include UNICEF UK, Breast Cancer Now, Trussell, Woodgreen, The Royal Academy of Arts, Zoological Society of London, Historic Environment Scotland and Fauna & Flora. We are part of TPXimpact, a Certified B Corporation and digital transformation company, whose 130-person team spans product leadership, design, user experience, engagement, engineering and strategy. Our work supports charities, non-profits, membership organisations and other purpose-led clients. This Principal Engineer role works across our client estate rather than being embedded in one project. It is UK-wide, with an advertised salary of £65,000–£75,000 per annum.

last updated 39 week of 2026