Product Engineer (Backend/AI @Briink)

Merantix; Greater London; On-site; GBP 90,000 - 140,000; Part time

Job summary

Briink is seeking a Backend/AI Product Engineer to join a small, high-ownership team building AI-powered sustainability tools for professionals in London. You’ll own problems end to end, from discovery and design through implementation, deployment, measurement and iteration.

You’ll design scalable backend systems, build AI capabilities with LLMs and RAG, and collaborate closely with product, data and customers to ship real value quickly in a fast-moving startup environment.

Qualifications

• Fluent English (C1+) written and spoken.
• Strong backend engineering experience with production systems.
• Experience designing APIs, databases, and enterprise-scale software.
• Cloud and container experience for deploying scalable workloads.
• Proficiency in Python (or similar) and willingness to learn Python quickly.
• Solid software-quality mindset: testing, CI/CD, observability, reliability, security.
• Experience in a small, high-ownership product team (startup/scale-up).
• Shipped end-to-end products, not just components.
• Applied AI/LLM experience: RAG, tool use, agents, evaluation systems.

Responsibilities

• Own product features end to end from user problem to delivery and improvement.
• Design and build scalable backend systems with APIs, data models, and workflows.
• Build and ship AI/LLM features including RAG, tool-using agents, and evaluation pipelines.
• Create reusable platform building blocks supporting multiple user journeys.
• Improve robustness, reliability, testing, observability, performance, and maintainability.
• Collaborate with users, product, and data teams to validate solutions.
• Prototype and test new AI capabilities to accelerate roadmaps.
• Contribute to team decisions with thoughtful opinions and constructive challenge.
• Work closely with engineers through pair programming and design discussions.

Skills

Fluent English

Backend engineering

APIs design

Databases design

Cloud & containers

Python

Testing/CI/CD

Startup/scale-up experience

End-to-end product shipping

Applied AI/LLM experience

RAG/LLM features

LangChain/LangSmith experience

ESG knowledge

FastAPI

PostgreSQL

Background queues

Tools

LangChain

LangSmith

LLM frameworks

FastAPI

PostgreSQL

Background queues

Job description

• As Briink’s Backend/AI Product Engineer, you’ll join a small, high-ownership product and engineering team building AI-powered products for sustainability professionals
• This is not a narrowly scoped backend role. You’ll take meaningful product problems from initial discovery and user conversations through technical design, implementation, and iteration to deploy them at scale across the ESG market
• You’ll combine strong backend and AI/LLM engineering with product judgement and the initiative to work out what should be built - not just how to action a predefined ticket
• Own product features end to end, from understanding the user problem and defining the right approach through to delivery, measurement, and improvement
• Design and build scalable backend systems, including APIs, data models, workflows, and infrastructure for complex enterprise products
• Build and ship applied AI/LLM features, such as LLM chains, RAG systems, tool-using agents, structured-output pipelines, and evaluation workflows
• Create reusable, extensible platform building blocks that support multiple user journeys and reporting workflows rather than solving each problem in isolation
• Improve the robustness of our systems, strengthening reliability, testing, observability, performance, and maintainability as we scale
• Work directly with users, product, and data, using qualitative feedback and product data to understand the real problem and evaluate whether a solution works
• Prototype and test new AI capabilities, turning promising ideas into practical product improvements that accelerate our roadmap
• Bring thoughtful opinions and constructive challenge, helping the team make better product and technical decisions
• Collaborate closely with other engineers, including through pair programming, technical design discussions, and shared problem-solving

• Fluent English (C1+), both written and spoken
• Strong professional backend engineering experience, with a track record of designing and shipping reliable production systems
• Strong API, database, and systems design skills, with the ability to model complex workflows and build maintainable foundations for enterprise products
• Cloud and container experience, with an understanding of how to deploy, operate, and scale production workloads
• Strong experience in Python (or another modern backend language such as Java, Ruby, or TypeScript, combined with the ability and willingness to become productive in Python quickly)
• A solid software-quality mindset, including testing, code review, CI/CD, observability, and pragmatic approaches to reliability and security
• Experience in a small, high-ownership product team, ideally within a startup or scale-up engineering organisation of roughly 5–20 engineers
• Evidence that you have shipped meaningful products end to end, rather than owning only a narrow component within a much larger organisation
• Applied AI/LLM experience: you have experience or a strong interest in LLM-powered features, ideally involving RAG or retrieval, tool use, agents, structured outputs, or evaluation systems
• Sharp and curious: You learn quickly, ask good questions, and enjoy getting to the root of difficult product and technical problems
• Pragmatic and action-oriented: You can move from ideas to experiments to production without waiting for perfect requirements
• Opinionated but open-minded: You challenge ideas constructively, welcome pushback, and enjoy thinking through problems with others
• A product-minded builder: You think beyond the task in front of you, focus on the user’s real problem, and care about whether what you ship creates value
• Kind and collaborative: You treat people well, communicate clearly, and help create a supportive, low-ego team environment
• Mission-driven: You care about using technology to accelerate sustainability and climate action
• Commercially aware and creative: You balance technical quality with user needs, business value, and speed
• Highly self-directed: You thrive in a fast-moving environment with autonomy, ambiguity, and limited oversight
• Experience building workflow, reporting, questionnaire, or other complex B2B SaaS products
• German language skills
• Experience improving latency, cost, and reliability for AI workloads
• Any experience with LangChain, LangSmith, or other LLM frameworks
• Knowledge of ESG, sustainability, climate tech, or corporate reporting
• Deeper experience with RAG, retrieval, agents, LLM evaluation, and production AI systems
• Familiarity with backend technologies such as FastAPI, PostgreSQL, background queues