Founding Engineer (Full-Stack)

Primary Location: London · Canary Wharf HQ (on-site). We plan to open a US office in the next ~6 months and will sponsor transfer visa for team members open to relocation.

Plexe is building AI agents that turn simple plain-English prompts into full production ML applications, including data pipelines, models, and more. We're backed by Y Combinator (X25) and were named one of the spring batch's "Top-10 AI agent startups" by Business Insider.

We're looking for a full-stack engineer with hands-on experience in building and deploying LLM-based products from scratch. You'll develop multi-agent systems, build product front-end and backend APIs, and ultimately create AI agents that autonomously handle the entire ML development lifecycle.

Responsibilities

• Product Development: build distributed ML infra, multi-agent systems, observability, client-facing APIs, and more - eventually owning your own product or product lines.
• Technical Leadership: drive technical decisions and architecture design, helping shape the foundations of our platform.
• Cross-Functional Collaboration: work closely with co-founders to translate business vision and customer feedback into actionable engineering plans.
• Ownership: take full product ownership from ideation to launch, including integration into existing systems. Your roadmap is one quick chat away from reality.

Qualifications

We don't have strict "formal" requirements - we just want to see you're awesome and up for the challenge! That might look like this:

Must-Have:

• 3+ yrs building ML/AI systems that served real users.
• Strong Python; comfort with AWS, Docker, Terraform/CDK, Postgres, etc.
• Experience with React, FastAPI, or other common web frameworks.
• An understanding of core concepts in ML, data science and MLOps.

Nice-to-Have:

• Built agentic workflows / LLM tool-use.
• Experience with MLFlow, WandB, LangFuse, or other MLOps tools.
• Experience with AirFlow, Spark, Kafka or similar.

Why Plexe?

• Hard problems: we're automating the entire ML/AI lifecycle from data engineering to insights.
• High ownership: first 5 engineers write the culture as well as the code. You have the power to fix whatever issue you can point at.
• Exciting environment: work at a fast-paced YC-backed startup with one foot in Silicon Valley.
• Location and compensation: sweet office in central Canary Wharf; equity that can matter.