Principal Software Engineer (PHP Full Stack)

About the role

About Smart Working

At Smart Working, we believe your job should not only look right on paper but also feel right every day. This isn’t just another remote opportunity - it’s about finding where you truly belong, no matter where you are. From day one, you’re welcomed into a genuine community that values your growth and well-being.

Our mission is simple: to break down geographic barriers and connect skilled professionals with outstanding global teams and products for full-time, long-term roles. We help you discover meaningful work with teams that invest in your success, where you’re empowered to grow personally and professionally.

Join one of the highest-rated workplaces on Glassdoor and experience what it means to thrive in a truly remote-first world.

About the Role

As a Principal Software Engineer (L6), you will shape technical direction across a significant product area within a fast-growing UK PropTech business based in Manchester. You will help develop technology that enables thousands of UK estate agencies to generate leads, streamline operations and grow market share, while remaining hands-on with engineering delivery.

You will work closely with engineering teams, product stakeholders, senior leadership and the technical leadership network to influence architectural decisions, identify emerging challenges and drive long-term technical improvements. This is an individual contributor role with an ideal 50/50 front-end and back-end balance, focused on technical leadership rather than people management.

Engineering operates with an AI-native approach, where agents write most of the code and engineers direct the work. You will help shape this approach through sound technical judgement, effective governance and engineering practices that support scalable, secure and maintainable products.

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Responsibilities

Set technical direction across a product area, determining which systems should be developed, how they integrate and which should be retired, while remaining hands-on with engineering.

Proactively identify emerging technical challenges, anticipate future growth constraints and lead solutions across multiple engineering teams.

Lead architectural decisions involving shared services, platform components and system boundaries, taking ownership of technical reviews for significant changes.

Identify and address scalability bottlenecks, operational inefficiencies and security risks using data-driven approaches to improve engineering delivery.

Drive the development and adoption of AI agents, shared plugins and AI infrastructure integrated into continuous integration and code review workflows across the engineering function.

Establish AI governance, safe-use standards and technical guardrails, including making informed build-versus-buy recommendations for AI investments.

Lead complex platform changes, major framework upgrades, security architecture initiatives and estate-level improvements in infrastructure cost and reliability.

Align multiple engineering teams around technical decisions, shared standards and long-term architectural outcomes.

Co-own product outcomes by proposing improvements that product teams adopt and translating technical trade-offs into commercial recommendations for leadership.

Collaborate with product stakeholders, engineering leadership and the technical leadership network during discovery and design to shape product and technical direction.

Mentor engineers across teams, establish engineering standards and develop shared tooling that improves engineering practices beyond an individual team.

Work independently on ambiguous, open-ended technical challenges, identifying problems before they affect teams and delivering practical, maintainable solutions.

Make thorough, data-driven technical decisions with long-term product and business impact, adapting quickly to unfamiliar teams and codebases.

Requirements

Extensive commercial software engineering experience, with 8+ years as a seniority guideline rather than a strict minimum.

7+ years of deep commercial PHP experience at expert level. Commercial PHP experience is essential; candidates with experience exclusively in other programming languages cannot be considered.

5+ years of expert-level experience with Laravel, Symfony or another PHP MVC framework.

3+ years of expert-level experience leading architecture and technical design across multiple teams or systems. Architectural leadership limited to a single team is insufficient for this position.

5+ years of expert-level experience designing scalable and distributed systems.

1+ year of advanced experience with AI-native software development, including Claude Code or comparable agentic coding tools used daily in production.

1+ year of advanced experience applying AI development best practices, including context management, token cost management and reviewing AI-generated output.

1+ year of advanced experience building AI tooling, agents or infrastructure used by other engineers, such as shared plugins, continuous integration integrations and automated review workflows.

Proficiency in AI governance and guardrails, including understanding failure modes, agent drift, safe-use standards and build-versus-buy decisions.

3+ years of experience with a modern JavaScript framework, preferably Vue 3 or React. Angular or a comparable framework may also be considered.

4+ years of advanced production cloud experience, preferably AWS, including influencing infrastructure cost, reliability and security across a cloud estate. Transferable expertise from another cloud platform is accepted.

Advanced experience delivering complex platform changes, major framework upgrades and security architecture improvements.

Strong product and commercial judgement, with the ability to connect technical decisions to business outcomes.

Advanced communication and influencing skills, with experience collaborating across multiple engineering teams and engaging senior leadership.

Experience mentoring engineers, establishing technical standards and developing shared tooling beyond an individual team.

Demonstrated ability to independently identify ambiguous cross-team technical challenges and lead architectural solutions through to delivery.

Ability to balance long-term architectural direction with hands-on engineering and detailed technical reviews.

Comfortable working independently, collaborating across teams with competing priorities and establishing standards in ambiguous environments.

Strong analytical and data-driven decision-making skills, with a focus on maintainability, scalability, security and long-term business impact.

Willingness to pursue a senior individual contributor career path focused on technical leadership rather than direct people management.

Eligibility to live and work in the UK.

Ability to work in a hybrid arrangement, attending the Manchester office at least twice per month. Candidates based further away may be considered if they can meet this requirement.

Nice to Have

Working knowledge of AWS services, including ECS, RDS, SQS, Lambda and EventBridge.

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£75,000 - £90,000 a year

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