Principal Full Stack Engineer - Full or Part Time
AI in this role
About us
You've probably heard of Autotrader, but do you know what we're all about?
We're the most trusted, most visited automotive marketplace in the UK. A heritage brand and a tech innovator. We bring together vehicle buyers and sellers to give them real choices. Cars may be what we're best known for but we’re also the place for pretty much everything else on wheels, from e-bikes to caravans.
In the automotive world, change is a constant, that’s why we take our job of untangling the complex car-buying journey very seriously.
At our core, we’re all about people. We go our own way while embracing diversity and celebrating our differences. We dedicate ourselves to the idea that we work better together.
Autotrader is a beautiful, surprising and vibrant place to work. We might not be for everyone, but we could be perfect for you.
About the job
We’re looking for Principal Full Stack Engineers to join us! Our technology teams combine a diverse set of technologies to meet the needs of our users, handling millions of requests a day across over 600 systems. We build these systems with industry standard frameworks and tools, such as React and Angular on the front end and Java, Spring Boot, Cloud SQL and Apache Kafka on the back end. All of this runs on our cutting edge cloud delivery platform, facilitating over 60k releases to production a year.
We’re a close-knit tech community where collaboration and knowledge sharing are at the core of what we do. Regular pair programming, code reviews, and stand-ups ensure that our engineers stay connected and aligned. As a Principal Engineer, you’ll play a visible, strategic role in driving system design and architecture decisions, mentoring team members, and helping our teams deliver high-quality solutions at scale. We actively encourage AI-assisted workflows. Whether it's using GitHub Copilot to eliminate boilerplate or LLMs to bounce ideas around, we give you the tools to move faster and focus on the hard engineering problems.
You might think that "Autotrader" means we’re looking for car enthusiasts, but that’s not the case. We’re looking for people who are passionate about technology, thrive in a collaborative environment, and have a genuine curiosity about solving complex problems.
What we’re looking for:
- Strong experience working across the stack, from designing scalable back-end systems to developing responsive front-end applications
- You should be comfortable working with Java, Spring Boot and the Java ecosystem / JVM
- Ability to architect and design complex, distributed systems that are scalable, maintainable, and performant
- Experience with modern front-end technologies (e.g., React or Angular, TypeScript/Modern JavaScript), along with proficiency in building RESTful APIs and web services.
- Strong knowledge of relational databases (SQL), along with experience working with document-based storage solutions (e.g., MongoDB)
- A structured approach to development and testing (including Test-Driven Development) with a focus on continuous delivery and automation
- Proven experience leading and mentoring teams, helping others grow technically while delivering high-impact projects
Although not a requirement, helpful experience includes:
- An interest in working with data at scale using tools like dbt, Spark, and AI/ML frameworks (e.g. PyTorch, TensorFlow, scikit-learn)
- Experience with Kafka or other event-driven architectures.
During our application process, you will be asked two questions to help us learn more about you and how you align with our values. These will be used as part of our selection criteria, to determine if we progress your application further
Benefits
We’re offering a salary of £60,000 – £80,000, plus an additional 10% of your salary awarded to you in shares each year. These awarded shares will become yours in yearly instalments over the next three years, and you can choose to either sell them or keep them as shares. And you'll receive 28 days holiday, plus bank holidays and comprehensive private medical cover.
That’s not all. You'll be enrolled in our pension scheme, where our standard contributions are 7% and employee contributions are 5%. We also have comprehensive private medical cover, enhanced family leave provisions, a car salary sacrifice scheme, share-save options, and much more.
We always want to give you the support you need and help prioritise your wellbeing, that’s why we provide access to 24/7 online GP and dentist, as well as specialist support for assisted fertility, gender dysphoria, menopause, period care plans and lots more.
On top of all that, our hybrid model, Connected Working, combines the best of both worlds – office and home working. You'll spend a minimum of 3 days a week in the office with your team, focused on collaboration and connection.
Additionally, we have our remote-first periods at set times during summer and winter. During these periods, you can work remotely anywhere in the UK and from certain locations abroad.
Discover more about our hiring process and explore our Engineering Blog.
#LI-CI1
#LI-Hybrid
How we rate this
Principal Full Stack Engineer - Full or Part Time at Auto Trader rates 15 out of 100 for how much of the daily work is AI. That makes it Little AI (AI Level 1 of 4). The level is about AI in the job, not seniority.
Little AI. AI is not part of the work.
- ●●●● Builds AI80 to 100
- ●●●○ Works on AI60 to 79
- ●●○○ Uses AI40 to 59
- ●○○○ Little AI0 to 39
Levels come from how often the tools, models and workflows of the role are named in the posting itself. Open the description and count.
Prepare for this job
A free preview built only from this posting: what it asks for, what you could be asked in an interview, and how to adjust your resume.
Skills and AI tools this role asks for
Questions you could be asked
- What's a project where you used Copilot hands-on?
- Walk me through how you've used PyTorch in your day-to-day work.
- What are the limits of TensorFlow that you've run into, and how did you work around them?
- What's a project where you used scikit-learn hands-on?
Adapt your resume
- List these exact terms on your resume: Copilot, PyTorch, TensorFlow, and scikit-learn. An applicant tracking system matches the wording, not the idea.
- Attach one line of real, concrete experience to at least one of them — a tool named with nothing behind it rarely survives a human read.
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