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

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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.

• 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.

• 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.

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