AI Research Engineer, StackOne
Tool Calling Safety
Plus share options plan
2 days a week in office
Unified API for B2B SaaS
Be an early applicant
Unified API for B2B SaaS
21-100 employees
Be an early applicant
Plus share options plan
2 days a week in office
21-100 employees
Company mission
To empower SaaS companies to build groundbreaking products that seamlessly connect with their customers’ stacks.
Role
Who you are
- Knowledge of prompt injection, sandboxing, and least-privilege patterns
- Experience building or auditing APIs, plug-ins, or protocol runtimes
- Ability to design and evaluate defences for real-time agent systems
- Background in Gen AI, with experience with Tool Calling
- Interest in security engineering, or applied cryptography
- Desire to work in a fast-paced startup, taking ownership of projects e2e and bias towards shipping
What the job involves
- We’re looking for an AI Research Engineer to secure the next generation of tool-calling for LLMs
- You’ll research and prototype defences that limit the attack surface of emerging standards such as MCP servers, and make tool execution safer against prompt injection and malicious calls
- You’ll work with our researchers on state-of-the-art tool-calling models, and with our engineers on the execution engine that runs them
- 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
- Investigate vulnerabilities in tool-calling protocols (MCP, OpenAPI, custom plug-ins)
- Design and test mechanisms to restrict malicious or unsafe tool calls
- Collaborate on the architecture of a secure tool execution engine
- Partner with the core research team to align safety work with model quality
- Design and manage synthetic data generation workflows to augment real-world datasets
- 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
- 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
Salary benchmarks
Our take
The explosion of SaaS tools has created an integration nightmare for companies. More and more B2B customers are expecting their SaaS tools to integrate with each other natively. But building and managing API connections in-house as a software vendor is time-consuming and costly, diverting teams from their core roadmap and stopping sales teams from selling.
As the next-generation integration platform, StackOne is solving the challenge of building SaaS integrations at scale once and for all. Founded in 2023 by ex-Google and Oracle executives, StackOne has seen exceptionally fast growth since its launch. With its best-in-class security and real-time architecture, the company is well-positioned to become a category leader in the API integration solutions market.
Steph
Company Specialist at Welcome to the Jungle
Insights
Company
Employee endorsements
Hard working team
"Each team member is approachable and happy to help, contribute or answer questions. There's a great sense of unity toward a common goal, and I trust..."
Funding (last 2 of 3 rounds)
Apr 2025
$20m
Series A
Nov 2023
$3.6m
Seed
Total funding: $23.9m
Company benefits
- Participation in the company’s employee share options plan
- 25 days holiday + 1 additional day holiday per year of tenure
- Remote working friendly
- £1,000 for your home office set up + £500/year top-up
- Cycle2Work and Electric Car Scheme
- Multiple company offsites per year
- Private health insurance (including dental & optical)
- Health, fitness and gift card discounts
- Annual team offsite to sunny spots (last ones were in Spain and Portugal)
Company HQ
Central London
Articles
Leadership
Romain Sestier
(Co-Founder & CEO)Previously worked for Google as co-founder and Product Lead of Area120, VP of Product and Sales at Yieldify, co-founder and CEO of Upper.ai and Head of UK Professional Services at ContentSquare.
Guillaume Lebedel
(Co-Founder & CTO)Previously VP of Engineering at Yieldify until its acquisition by Epsilon/Publicis. Also co-founded another start-up and worked at Maxymiser (acq. by Oracle) as a developer.
Share this job
View 13 more jobs at StackOne