Head of Platform Engineering

Job Description

Who are OnCommerce?

OnCommerce is a global selling platform that powers a growing network of retail channels, including:

• OnBuy - The only marketplace in the world to give customers instant Cashback on everything
• easyShop - An all-new marketplace created in collaboration with the easy® family of brands
• Comet - The iconic UK tech brand making its return later this year

OnCommerce is growing fast, launching new brands and scaling to power the future of ecommerce.

Be Part of the Story

OnCommerce is constantly evolving. Everyone here plays a hands-on role in shaping what comes next, building brands that make an impact across global markets. There’s no red tape or rigid corporate structure; just smart people taking ownership and figuring things out as we build something big together. The pace is fast, priorities shift, things aren’t always perfectly set up, and you’ll often need to get stuck in and solve problems. But if you thrive in that kind of environment, you’ll have real influence, real ownership, and the chance to grow with a rapidly scaling business.

Why This Role Exists

OnCommerce is transforming its platform and operating model while continuing to trade live, every day, across Buyer and Seller domains. That dual demand, build the future, protect the present, doesn't run itself. This role exists to hold both at once: the standard the engineering team is held to, the resilience of what's live today, and the continuity of delivery and culture as the organisation restructures around it.

Role Overview:

This is a senior leadership role accountable for the day-to-day performance and long-term evolution of OnCommerce’s engineering function, spanning both the current platform and its transformation to a modern, composable architecture.

The Head of Platform Engineering owns engineering delivery, operational resilience, and standards across all squads, ensuring strong processes translate into reliable services, predictable delivery, and high-performing teams.

Working alongside the Transformation and Solution Architecture Leads, you will balance live operations with platform evolution, ensuring neither stability nor progress is compromised.

Success in this role requires leading people, setting clear expectations, and driving accountability for outcomes, while making effective trade-offs between short-term delivery and long-term sustainability.

Key Responsibilities

Product Engineering Ownership & Accountability

• Define and enforce clear ownership boundaries across the engineering team, by domain (Buyer / Seller / Platform), holding every contributor accountable regardless of sourcing model (permanent or partner-led)
• Track and report Throughput and Instability per domain, so standards are visible and enforceable, not aspirational

Transformation Continuity

• Hold delivery consistent through every point of disruption the transformation introduces: nearshore/offshore onboarding, domain moves, headcount change
• Partner with the Transformation Lead to ensure structural change doesn't degrade live delivery

Standards & Engineering Governance

• Own the engineering standard across both the current platform and the target state
• Review the Transformation Lead's roadmap for engineering-standard and operational impact before commitments are made
• Own how modern and legacy architecture coexist during migration, guarding against legacy practices and assumptions leaking into the new platform

People Leadership & Team Engagement

• Lead and develop engineering capability across squads (including DevOps and platform functions)
• Coach and support Tech Leads to build consistent leadership standards across teams
• Foster a culture of ownership, accountability, and continuous improvement
• Identify capability gaps and support hiring, development, and succession planning
• Own resource planning, including capacity, skills mix, and on-call structure

Operational Resilience & Incident Ownership

• Establish and run a two-tier resolver model: Ops on-call for standard support and runbook-driven issues, Product Engineering (Buyer/Seller) as the resolver group for genuine engineering problems
• Build rota depth (minimum 3 engineers per domain, or full team where smaller) so resolution doesn't depend on any one individual
• Drive a genuinely blameless Post-Incident Review culture, building on the existing Incident Management SOP

Security & Risk

• Embed secure coding practice, SAST/DAST scanning, and OWASP-aligned standards into the engineering definition of done
• Surface security risk in business terms (exposure, cost to fix vs cost to carry) and route it to the appropriate decision-maker, rather than carrying risk-acceptance decisions unilaterally

Technical Debt Management

• Identify, log, and manage technical debt within day to day delivery
• Escalate strategic trade-offs (rebuild vs patch, roadmap sequencing) to the Solution Architecture Lead, owning visibility and routine remediation rather than the strategic call

Delivery & Execution

• Work with Product Owners (Buyer and Seller) to translate roadmap items into scoped, sequenced engineering execution
• Own technical design and implementation choices day to day, operating within established architectural patterns without requiring sign-off for routine work
• Escalate to Product Owner Heads where scope or trade-off decisions sit above the Product Owner's remit

Requirements

Essential

• Strong full-stack engineering background with Laravel/PHP, comfortable across monolith and microservices patterns

• People leadership: hiring, mentoring, performance management
• Direct experience leading an engineering transformation, restructuring teams, process, or architecture, while keeping a live, revenue-generating platform running throughout
• Strong API design and system architecture experience
• Production experience with MySQL, Couchbase or MongoDB, and Redis
• GCP, deploying and operating live services at scale
• Experience balancing legacy support against parallel investment in a target architecture
• Startup or scale-up experience, comfortable operating with ambiguity and limited resource

Desirable

• Has lived through a MACH or composable architecture migration on a live, trading platform, not greenfield, and carries the scars: knows where the pain actually shows up (data consistency across services, search/catalogue re-platforming, vendor lock-in regret)
• Multi-cloud or cloud-agnostic experience, enough to have an informed, opinionated view on GCP versus alternatives rather than default loyalty to whatever's currently in place
• Comfortable working beyond PHP where the future stack calls for it (e.g. Node.js, Go, Python)

Benefits

The salary on offer for this role is upto £100k per annum depending on experience.

We also offer the following benefits:

• Company Equity- In return for helping us to grow, we’ll offer you company equity, meaning you own a piece of this business we are all working so hard to build.
• 25 days annual leave + Bank Holidays
• 1 extra day off for your Birthday
• Employee Assistance Programme
• Perks at Work benefit platform
• Opportunities for career development and progression

This role is UK remote or Hybrid if you live near our Manchester or Bournemouth's offices.

Our Commitment

OnBuy is an equal opportunities employer. We are dedicated to creating a fair and transparent workforce, starting with a recruitment process that does not discriminate on the basis of gender, sexual orientation, marital or civil partnership status, pregnancy or maternity, gender reassignment, race, colour, nationality, ethnic or national origin, religion or belief, disability, or age.

Just a heads up — we never use WhatsApp. or any messaging apps to contact candidates If someone reaches out this way, it isn’t us and let the recruitment team know.