Senior Backend Engineer | AI Platform
AI in this role
Millions of people want to grow their money but don't know where to start. More than 90% of adults don’t access traditional financial advice. That's the gap Plum was built to close.
We're building the proactive money platform that makes it easy for people to smartly and sustainably grow their money. Whether you're stashing the cash for tea and toast in your first home or catching some rays during retirement, we've got your back.
Since 2016, millions of people across 10 European markets have set aside more than £10 billion with Plum. But what we're most excited about is what comes next and the opportunity for our people to help shape it.
We're now going after something even bigger: the £2 trillion+ advised market in the UK and beyond, currently locked behind high fees and complexity. By combining AI-driven financial guidance with the products people actually need, we're building a solution for everyone, not just the wealthy few.
At Plum, you'll be part of a team that's ambitious, curious and driven. We move fast, learn from what doesn't work, challenge the status quo and, most importantly, build something that makes people's lives better. We believe great ideas can come from anywhere, and that the best work happens when people feel trusted to take ownership, collaborate openly and bring their whole selves to work.
Join nearly 300 Plumsters and be part of a team shaping the future of money
The Role
As part of the AI Platform team, you will play a key role in building the foundational infrastructure, frameworks, and tooling that enable AI-powered products and capabilities across the organization. This role requires a high degree of autonomy and ownership, as you'll be responsible for designing scalable solutions that empower multiple engineering teams while ensuring reliability, observability, and cost efficiency.
What are we looking for:
- 5+ years of experience in Software Engineering, Backend Engineering, or Platform Engineering.
- Strong experience building and maintaining backend systems and distributed services in production environments.
- Experience designing developer platforms, internal tooling, shared services, or infrastructure that supports multiple engineering teams.
- Hands-on experience building AI-powered applications and services using modern LLM frameworks and agentic architectures.
- Good understanding of modern AI concepts and practices, including:
- Large Language Models (LLMs)
- Retrieval-Augmented Generation (RAG)
- Prompt Engineering
- AI Guardrails
- AI Evaluation Frameworks
- Experience with AI frameworks such as Agent Development Kit (ADK), LangChain, LangGraph, CrewAI, or similar.
- Experience working with cloud platforms such as Google Cloud Platform (preferred), AWS, or Azure.
- Strong understanding of system reliability, observability, monitoring, and incident management.
- Experience with Infrastructure as Code and cloud-native architectures.
- Previous experience working within a Platform Engineering team is a strong plus.
Key responsibilities:
- Design, build, and maintain a robust, scalable, and cost-effective AI Platform that supports AI initiatives across the organization.
- Develop and maintain internal frameworks, libraries, and services used by multiple product squads.
- Establish and promote best practices around prompt engineering, AI guardrails, and AI evaluation methodologies.
- Build platform capabilities that enable teams to safely deploy, monitor, and iterate on AI-powered applications.
- Configure and maintain tracing, monitoring, observability, and incident management solutions to ensure platform reliability.
- Partner closely with product and engineering teams to understand their needs and provide scalable platform solutions.
- Continuously improve developer experience and platform adoption across the organization.
Tech Stack:
Backend
- Python
- FastAPI
- Agent Development Kit (ADK)
Datastores
- PostgreSQL
- BigQuery
- Firestore
Infrastructure
- Google Cloud Platform (GCP)
- RabbitMQ
- Terraform
Monitoring & Observability
- Grafana
- Prometheus
- Langfuse
- incident.io
- Sentry
What to Expect from Our Hiring Process
At Plum, we value a lot the time you devote to the hiring process, this is why we are always trying to make the process as fast and smooth as possible.
- 30 min. Call with ourTalent Acquisition Team. So we understand better your career plan, tell you more about Plum and the role ⚙️
- 45 min. Call with our Engineering Lead. Brief technical discussion about the role and your skills 🏄
- 120 min. Live Coding Call with our Engineers, including System Design exercise and an Implementation phase🧑💻
- 30 min. TeamCall with a Product Manager and a Senior Manager from Engineering, for you to understand the business and envision yourself as part of Plum 🧬
- Offer 💵
Plum's Perks
- Own part of the company you're helping grow through stock options
- Private health insurance
- Annual training budget
- Plum Premium for free
- Competitive referral scheme
- Flexible approach to remote working: we encourage at least 2 days a week in one of our beautiful offices in London, Athens or Cyprus
- Team breakfasts and team lunches
- 25 days holiday + bank holidays
- 45 work-from-anywhere days to give you flexibility to work your way
- 2 weeks sabbatical after 4 years to take the break you deserve
- Enhanced parental leave
- 1 paid volunteering day annually
- Annual team trip to a surprise destination!
- A fun, inclusive company culture (think 🦄🌈💯)
If you think this sounds like you, don’t hesitate to get in touch!
Thanks,
Plum Τeam 💜
*Plum is an Equal Opportunity Employer. Plum does not discriminate on the basis of age, race, religion, sex, gender identity, sexual orientation, non-disqualifying physical or mental disability, national origin or any other basis covered by appropriate law. All employment is decided on the basis of qualifications, merit and business need
How we rate this
Senior Backend Engineer | AI Platform at Plum rates 83 out of 100 for how much of the daily work is AI. That makes it Builds AI (AI Level 4 of 4). The level is about AI in the job, not seniority.
Builds AI. The job is building AI systems.
- ●●●● 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
- How do you structure and test a prompt to get consistent output from a language model?
- How would you design a retrieval step so the model answers from real data instead of guessing?
- How do you decide that one model's output is better than another's for a given task?
- What's a project where you used LangChain hands-on?
- Walk me through how you've used LangGraph in your day-to-day work.
Adapt your resume
- List these exact terms on your resume: Prompt Engineering, RAG, AI Evaluation, LangChain, and LangGraph. 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.
- Lead with what you built, trained or shipped — this role is judged on the AI system itself, not the tools around it.
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