Security Engineer (£70k-£110k + Equity) at StackOne

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers.

She will pick the best candidates from Jack's network.

The next step is to speak to Jack.

Job Title

Security Engineer

Salary

£70k-£110k + Equity

Company Description

StackOne is a $24M Series B AI integration gateway backed by GV and Workday Ventures. Based in London, they provide a unified API that allows SaaS platforms and AI agents to orchestrate hundreds of enterprise-grade integrations securely through real-time architecture, managed authentication, and end-to-end observability.

Job Description

As the first dedicated Security Engineer at StackOne, you will own the cloud and product security posture end-to-end. Reporting to the CTO, you will build security tooling in TypeScript/Python, harden AWS/Cloudflare infrastructure, and threat-model features handling complex OAuth flows. You’ll enable engineers by automating security directly into the SDLC.

Location

London, UK

Why this role is remarkable

First security hire opportunity: Define the security architecture and strategy from the ground up for a high-growth AI infrastructure startup.

High-caliber backing: Supported by top-tier investors like GV and Workday Ventures with $24M raised to scale the future of agentic integrations.

Builder-centric culture: This is a hands-on DevSecOps role where you ship production code and tooling rather than just managing GRC checklists.

What You Will Do

Own the secure SDLC by driving SAST, dependency scanning, and secrets detection standards across all repositories and CI/CD pipelines.

Harden the AWS and Cloudflare estate using zero-trust patterns, network segmentation, and advanced IAM/KMS configurations for multi-tenant environments.

Threat-model new product features, connector executions, and agent tool-calling paths to ensure robust security for complex authentication and OAuth flows.

The ideal candidate

3+ years of security engineering experience with deep hands-on expertise in AWS security services like GuardDuty, Security Hub, and KMS.

Proficiency in shipping production-grade code using TypeScript, Python, or Go, with a strong background in Infrastructure as Code (CDK or Terraform).

Solid understanding of application security, including OWASP Top 10, threat modeling, and securing B2B SaaS multi-tenant environments at scale.

Who are Jack & Jill?

Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.

And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.

How does this work?

Jill is the AI recruiter working for the company. She recruits from Jack's network.

If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives.

We never post fake jobs

This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network.

Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description.

We appreciate this can make them look a bit suspect, but there isn't much we can do about it.