Senior Software Engineer

Location: 1-2 days per week in the London office

Who are we?

We’re the original pioneers in connected commerce marketing. Since 2008, we’ve been partnering with major retailers, powering global brands, and building meaningful connections with shoppers.

We simplify the mind-boggling complexity of today’s retail media landscape. We deliver impactful campaigns that connect with people where it matters. We create seamless and personalised shopping experiences. Above all, we deliver amazing results for our partners, driven by our unshakeable desire for growth. Time after time, we change the game. SMG is home to a world-class suite of commerce advertising capabilities powered by data and cutting-edge technology. We constantly push ourselves, our tech and our industry to discover innovative new ways to connect, sell and grow.

About the role

The Senior Software Engineer is the technical anchor of a Plan-Apps squad. The role is hands on and remains firmly in the codebase, but the defining contribution is not throughput: it is the technical direction of the work and the standard of engineering around them.

This role owns the design of new features rather than the implementation of someone else's design. It is the person the squad turns to when a problem is ambiguous, when a decision carries architectural consequences, or when a piece of the platform needs to be reasoned about beyond the ticket in front of them. It is also the person who raises the level of the engineers around them, through review, pairing, coaching and example. Most of what this role builds is new. SMG is solving problems our users face today by designing and standing up new services, and the Plan-Apps ecosystem is becoming service oriented and more data centric as we do it, with new data warehousing and clearer boundaries between services. Senior engineers shape what those services are and how they fit together, rather than working around an estate that is already fixed.

What you’ll do

• Design and stand up new services that solve real user problems, setting their boundaries, interfaces and data ownership so they fit the wider Plan-Apps estate.

• Define the code architecture for new features within the squad's domain, and take end to end ownership from design through implementation to production deployment.

• Make and justify technical decisions with an understanding of their longer term cost.

• Break down ambiguous or poorly specified problems into deliverable work for the squad.

• Contribute to shared libraries and reusable components, flagging where duplication is emerging.

• Act as a point of contact and learning for less experienced engineers; coach and guide them through review, pairing and day to day support.

• Provide technical leadership on projects, coordinating engineering effort across the squad.

• Contribute to hiring through technical interviews and assessment.

• Maintain and optimise our cloud infrastructure with attention to reliability, security, performance and cost.

• Build and improve CI/CD pipelines and automated testing within the deployment patterns

• Identify and drive improvements to code quality, developer experience and performance, making the commercial case as well as the technical.

• Provide technical input into requirements and tickets during refinement, surfacing feasibility, effort and risk.

What you’ll bring

• Significant hands on experience delivering at senior level, with a track record of owning features from design through to production.

• Deep knowledge of JavaScript and TypeScript, including strong command of React and Node.js.

• Demonstrable experience defining technical architecture for non-trivial features, and articulating the trade-offs behind those decisions.

• Evidence of raising the standard of engineers around you: mentoring, coaching, review culture, or leading a project team.

• Practical experience with NoSQL databases, ideally MongoDB, and comfort working with relational data.

• Strong cloud infrastructure experience: designing, deploying and optimising cloud infrastructure.

• Experience with containers, CI/CD pipelines and Infrastructure as Code such as Terraform.

• Strong grasp of security and performance considerations in production web applications.

• Excellent communication skills, including the ability to explain technical decisions to non-technical stakeholders.
  Desirable

• Experience line managing engineers, or clear readiness to take it on.

• Experience decomposing a monolith into services, or defining service boundaries in a distributed system.

• Exposure to data warehousing or analytical data modelling alongside transactional systems.

• Experience designing API-first architectures, webhook integrations or third party platform integrations.

• Familiarity with observability and SRE practice: monitoring, logging, tracing and incident response.

We're looking for people who enjoy the buzz of change, the satisfaction of building something better, and the joy of working with a close-knit, values-driven team. If you love variety, thrive in a fast-paced environment, and embrace change with energy, this could be your right role.

Don’t meet every single requirement? We still want to hear from you. If you believe you’d thrive in this role, your unique perspective might be just what we’re looking for.

Why SMG?

At SMG, we hire for the future, which is fast-moving and changing shape. Do you have the potential to help shape our business? We’re looking for brilliant, diverse talent who want to grow with us - people who are curious, ambitious, and eager to learn, whether as specialists or across teams.

We value those who take ownership of their growth and bring fresh perspectives. That’s why we’re committed to equity, inclusion, and building a place where everyone feels empowered to grow. At SMG, it’s not just about filling a role but building the future together.

● 10% discretionary bonus

● £1,800 yearly wellbeing fund (on top of your salary!)

● Free Headspace subscription

● £500 yearly “Uni Fund” for learning

● 4 extra Wellbeing Days off per year

● Annual Summer conference + year-round celebrations

● 4pm finishes every Friday

● Flexible and hybrid working

Useful Links Before You Apply

Our full data retention policy can be found here .