AI Engineer

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

StackOne sits behind the scenes as the integration layer providing thousands of tools,: 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 or small to enterprise companies building Agents to sell or to improve their own processes.

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 a Software Engineer with a strong background in AI production-grade applications with professional experience working with LLMs (eg: GPT, Anthropic and others).

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

• Act as a full-stack engineer: design, build, and ship features across frontend, backend, and infrastructure.

• Leverage AI models to accelerate development, while maintaining best-in-class reliability, testing, and code quality.

• Build and maintain inference pipelines, embeddings, retrieval, and orchestration systems.

• Integrate tool-calling and MCP (Model Context Protocol) patterns into product features.

• Ship and maintain open-source or internal TypeScript/Python packages.

• Work with AWS and/or Cloudflare to deliver scalable, secure, low-latency systems.

• Collaborate with product and design to deliver features end-to-end.

• Proven experience as a full-stack engineer.

• Expertise in TypeScript and/or Python.

• Strong background in building on AWS and/or GCP and/or Cloudflare.

• Experience building and shipping TypeScript/Python packages.

• Familiarity with tool-calling, agent frameworks, and MCP.

• Track record of shipping production systems with high code quality and reliability.

• Curiosity to push the boundaries of what AI-powered development can deliver.

• Past experience with Generative AI/LLMs and related technologies/frameworks

• Desire to work in a fast-paced startup, taking ownership of projects e2e and bias towards shipping.

• (Preferred): Experience working on/publishing CLIs & SDKs

You 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

• 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.