About StackOne

StackOne is the universal integration layer for modern SaaS products. We've raised $24m in 2 years, and we're backed by top tier investors like Google Ventures and Workday Ventures.

Our unified API platform lets vendors ship hundreds of native, white label integrations in days, not months, by abstracting away dozens of disparate third party APIs into a single, normalized interface. On top of those APIs, we provide AI Agent Actions so customers can build agentic workflows without wrangling OpenAPI specs.

StackOne sits behind the scenes as an embedded iPaaS: SOC 2 compliant, multi-tenant, and invisible to end users powering integrations for future-of-work SaaS categories such as HR, Compliance, and AI Agents.

Our customers are established B2B SaaS companies that:

• Sell to mid market and enterprise buyers
• Are building AI Agents in the near future
• Need deep, native integrations to win competitive deals and power their product
• Value time to integration over building connectors in house

We typically close OEM and embedded licensing deals, multi-year (1 to 3 year) contracts, five to seven figure TCV, with a strong land and expand model. Key buyer personas are the CPO and CTO.

About the role

We're building a world where users of any SaaS can integrate with the tool of their choice in one click thanks to StackOne. We're convinced AI is pivotal to making this a reality by transforming how SaaS talks to each other and this is what you will help achieve.

We are looking for an AI Research Engineer with deep expertise in large-scale model fine-tuning, dataset curation, and training infrastructure. Unlike our AI Engineer role, which focuses on applying and productionizing existing LLMs and agent frameworks, this role is focused on pushing model performance through fine-tuning, synthetic data pipelines, and large-scale experimentation.

You will own, design and run experiments on cutting-edge architectures, manage distributed training clusters, and help curate & generate high-quality datasets. This role sits closer to the research/ML infra side than product engineering, but with a strong mandate for applied, production-ready results.

In this role, you will work with wider AI team of StackOne (comprising of other researchers and engineers) and report directly to the CTO.

Responsibilities

• Own the full lifecycle of model fine-tuning projects (objectives, dataset prep, training, eval, deployment handoff).
• Design and manage synthetic data generation workflows to augment real-world datasets.
• Build and maintain large-scale training infrastructure (multi-GPU/TPU clusters, orchestration, optimization).
• Develop tools for dataset curation, labeling, filtering, and augmentation.
• Conduct benchmarking, and evaluations to measure fine-tuning impact.
• Collaborate with the rest of the engineering team to integrate fine-tuned models into production stacks.
• Stay ahead of research in parameter-efficient fine-tuning, synthetic data, and LLM training.

What we\'re looking for

• Background in deep learning, with emphasis on LLMs.
• Experience running large-scale distributed training jobs
• Understanding of synthetic data techniques and dataset pipeline design.
• Proficiency in evaluating LLMs with quantitative metrics and human evals.
• Desire to work in a fast-paced startup, taking ownership of projects e2e and bias towards shipping.
• (Preferred) Contributions to open-source ML libraries or published research in applied ML/LLM fine-tuning.

Our Stack

ou will have a lot of freedom and agency to chose and work with the technologies you love. Our tech stack includes:

• Infra & monitoring: AWS (ECS, RDS, Elasticache, Lambda etc.), Cloudflare, Tinybird, Modal, Dagster, Langsmith, Datadog, Sentry, Incident.io
• Languages & Frameworks: Typescript (Node.js), Python, NestJS, React, Svelte,
• Other day-to-day Tools: Postman, Notion, Slack, Jira, Github and more

Benefits

• 25 days holiday + 1 additional day holiday per year of tenure
• Participation in the company\'s employee share options plan
• Private health insurance (including dental & optical)
• Health, fitness and gift card discounts
• £1,000 for your home office set up + £500/year top-up
• Paid lunch in the office
• Annual team offsite to sunny spots (last ones were in Spain and Portugal )
• Join one of Europe\'s fastest-growing startups
• Work with a veteran team of ex-employees of Google, Microsoft, Oracle, Coinbase, JP Morgan and more
• Cycle2Work and Electric Cars scheme
• Hybrid work set up - typically 2d in the office

Ready to help us change the game for SaaS integrations? Get in touch and let\'s chat!

We believe diversity drives innovation. We encourage individuals from all backgrounds to apply. As an equal-opportunity employer, we celebrate diversity and are committed to creating an inclusive environment for all employees.