Senior Software Engineer

Who you are

• Strong senior-level software engineering: Proven experience owning complex components or services end to end, from design and implementation through testing, deployment, and operation
• Deep engineering fundamentals: Strong judgement around system design, concurrency, security, testing, and architecture trade-offs. Production Python experience is preferred
• Practical AI evaluation and safety experience: A critical understanding of LLM behaviour and experience building or using evaluation harnesses to measure output quality and reliability
• Security and governance mindset: Experience with areas such as threat modelling, authentication and authorisation, red teaming, data-access controls, or guardrails for internal platforms
• Cloud experience: Comfortable running services in AWS, owning reliability and scalability, and collaborating with platform, techops, and security teams
• Clear communication and collaboration: Able to explain technical trade-offs, challenge constructively, and turn complex safety and evaluation findings into practical action
• Evaluation and safety frameworks: Experience with tools such as Inspect AI, Ragas, OpenAI Evals, or NeMo Guardrails
• Backend engineering: Django experience and strong patterns for security, performance, and maintainability
• Observability: Experience using Datadog for tracing, monitoring, and investigating complex AI-enabled systems
• AI engineering tooling: Familiarity with tools such as Pydantic AI, LiteLLM, or LangChain

What the job involves

• We're hiring a Senior Software Engineer to join our newly formed Agent Safety / Evals team
• As AI agents take on more autonomous tasks across Kraken's internal workflows, you will help ensure they do so securely, predictably, and within clearly defined operational boundaries
• This is a hands-on senior individual-contributor role
• Working with the Lead Software Engineer and the broader AI team, you will own substantial parts of our evaluation, safety, and reliability stack - turning technical direction into production systems, contributing to architecture decisions, and raising engineering standards through thoughtful collaboration and mentoring
• Build internal agent-safety systems: Design and implement services that improve the reliability, security, and determinism of LLMs and autonomous agents, keeping them within expected operational boundaries
• Develop robust evaluation frameworks: Build scalable harnesses and evals for internal workflows and AI skills. Define meaningful test cases, interrogate output quality, and improve the reproducibility of the systems used to measure it
• Implement guardrails and governance controls: Develop pre- and post-generation controls and translate agreed governance requirements into maintainable software across internal tools and platforms
• Strengthen AI security and observability: Engineer authentication and permission patterns for internal agents, improve monitoring and tracing, and contribute to operational playbooks for AI-specific anomalies
• Support verification and red teaming: Design tests and participate in continuous verification and red-teaming exercises to identify prompt injection, data-access, and unpredictable-behaviour risks before they reach production
• Operate services in AWS: Deploy, run, and support high-throughput, low-latency safety services; make sound architecture, reliability, and cost trade-offs; and work effectively with platform, techops, and security partners
• Raise the engineering bar: Contribute to technical decisions, review designs and code, mentor other engineers, and help establish pragmatic patterns that can be reused across AI Foundations
• What Success Looks Like
• Reliable delivery: You ship well-tested safety and evaluation capabilities that are adopted by internal engineering and product teams
• High-quality evals: Evaluation harnesses produce meaningful, reproducible signals that reflect the real-world performance and safety of Kraken's internal AI tooling
• Resilient infrastructure: The services you own are observable, secure, scalable, and supported by clear operational practices
• Strong technical collaboration: You work effectively across AI Foundations and partner teams, improve designs through constructive challenge, and help others deliver safely and confidently

Benefits

• Equity option scheme: Everyone who works at Kraken owns a part of the business with shares in the Octopus Energy Group. So as the company grows we all benefit
• Pension scheme: We'll pay 5%. You decide on your contribution starting from 3%
• Holidays: We don't count your holiday days. We trust everyone to work hard and take as much time off as they need
• Flexible working: We're happy for you to work in a way that's best for you. Need to pick the kids up from school or work from home? That's not a problem. It's important to us that everyone has a positive work-life balance
• Free breakfast: Our offices are always stocked with fresh fruit, breakfast, snacks, great coffee and soft drinks.

Weekly on a Friday we all get together (including virtually) for company updates and drinks

• For parents: We can arrange access to tax free childcare, as well as maternity and paternity pay
• Free eye tests: We offer eye test vouchers for all colleagues who use Visual Display Units (VDU). Long spells of VDU work can be visually demanding so we want to make sure you're OK
• Car salary sacrifice: Save money on leasing an electric vehicle through our workplace salary sacrifice scheme
• Cycle to work scheme: Spread the cost of buying a bike, including accessories and safety equipment, up to a value of £2.5K. And save money on the repayments through the cycle to work scheme
• Get the right tech: Have a certain tech requirement? We’ll do our best to sort it for you
• Money coach: Get support with financial planning through our partnership with Octopus Money Coach
• Yoga + Headspace: Twice a week we have 45 Minute live yoga class open to all Kraken staff.

Need some calm in your life? We have Headspace licences available

• Team events and activities: Participate in team events and cohesion activities to build stronger connections
• Health Insurance: We’ll provide comprehensive coverage with Alan and access to Alan Mind.
• Transportation: If you cycle to the office we’ll support you by up to €600/year, if you use public transport we'll reimburse 75% of your Navigo pass. If you use both, we'll support you by up to €900/year
• Green energy discount: Enjoy a 32% discount on green energy compared to the regulated tariff
• Year-end gift voucher: Receive a €100 gift voucher at the end of each year
• Gymlib subscription: Get a subscription to Gymlib for access to a wide variety of fitness options
• Meal vouchers: Enjoy €10 Ticket Restaurant cards for meal expenses
• NGO support days: Benefit from three additional RTT days (Reduction of Working Time) to support NGO work, every year