---
title: 'Senior Platform Engineer at StackOne'
canonical: 'https://feeny.ai/job/senior-platform-engineer-stackone-london-v5g9mzhpmhcb'
type: 'job'
last_seen: '2026-09-06'
---

# Senior Platform Engineer at StackOne

- **Company:** StackOne
- **Location:** London, United Kingdom
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-06-01
- **Last confirmed live:** 2026-09-06
- **Apply:** https://jobs.ashbyhq.com/stackone/4bc85e1c-0308-4ed3-9f3c-c19c2b9e905a

## Job description

## About StackOne

StackOne is the integration infrastructure for AI agents. Backed by GV and Workday Ventures ($24M raised), we make it possible for any AI agent — whether our customers build it into their product or buy it off the shelf — to take real action across the enterprise stack. Our platform gives agents 430+ connectors and 26,000+ pre-built actions, an AI connector builder for everything not covered yet, and the production layer agents actually need: semantic tool discovery that cuts token use by up to 80%, managed authentication and per-action permissions, the most accurate prompt injection defense on the market, and end-to-end observability.

Join us on our fast trajectory to build the future of agentic integrations.

## ABOUT THE ROLE

We're looking for a Senior Platform Engineer to own how StackOne is built, shipped, and run, as we scale across our own cloud and into our customers' clouds. You'll own the infrastructure behind the platform, our deployment pipeline and developer tooling, and how we package StackOne to run inside customers' own AWS, GCP, or Azure accounts.

It's a hands-on role with broad scope. You write code and tooling, you own the IaC other engineers depend on, and you set the standard for how every new repository gets deployed and secured. You'll report directly to the CTO and work closely with our Security Engineer and tech leads.

## RESPONSIBILITIES

- Own our infrastructure at scale: the AWS estate today (ECS Fargate, Aurora, ElastiCache, MSK, OpenSearch, Lambda, KMS) and the AWS CDK to Terraform migration. Keep it reliable, observable, and cost-aware.
- Build out the deployment pipeline as we consolidate toward a monorepo: the CI/CD that ships every service, plus an automated end-to-end testing harness with incremental (affected-only) testing that stays fast as we grow.
- Ship into customers' own clouds (self-hosted / BYOC): the Terraform modules, container images, runbooks, and documentation for internal teams and customers.
- Own the release and upgrade path for self-hosted customers: versioned, signed releases, a supported-version policy, and a call-home for usage and version reporting.
- Set the standard for new repositories: partner with the Security Engineer and tech leads so new projects (product, internal tools, and vibe-coded prototypes) ship secure and deployable from day one. Templates and golden paths, not gatekeeping.
- Raise reliability: SLOs, observability, and incident response. Make the system easy to operate when something breaks at 3am.
- Treat infrastructure as a product: paved roads and self-serve tooling so product engineers ship without waiting on you.
- Use AI in the workflow: lean on LLMs and agents for IaC generation, test scaffolding, and runbook drafting, with guardrails you trust.

## WHAT WE'RE LOOKING FOR

- 4+ years in platform, infrastructure, SRE, or DevOps, with hands-on AWS at scale: ECS/Fargate, RDS/Aurora, Lambda, networking, IAM, KMS.
- Deep IaC ability: Terraform and hands-on AWS CDK or CloudFormation. Our estate is CDK today and migrating to Terraform, so you will work in both. You are comfortable owning modules other teams build on.
- Strong CI/CD and monorepo build experience: caching and incremental/affected-only test execution. You've made a slow pipeline fast.
- Strong coding in TypeScript, Python, or Go. You build tooling, not just YAML and configs.
- Containers and Kubernetes in production: Docker, and Kubernetes you have run yourself. Cluster setup, upgrades, resource limits, and the reasons a pod won't start.
- Security-minded: you bake secure defaults into pipelines and repo templates, and partner with security rather than routing around it.
- A clear writer: docs and runbooks that internal engineers and external customers can follow.
- End-to-end ownership: you scope, ship, and measure, and automate instead of running manual checklists.

## NICE TO HAVE

- Shipping software into customers' own cloud or on-prem (BYOC / self-hosted), or a platform like Nuon, Replicated, or Omnistrate.
- Multi-cloud (GCP or Azure) IaC, and exposure to Temporal, Kafka/MSK, ClickHouse, or OpenSearch.

## OUR STACK

- Cloud & infra: AWS (ECS Fargate, Aurora Postgres, ElastiCache, MSK, OpenSearch, Lambda, S3, KMS, CloudFront, WAF), GCP, Cloudflare (Workers, WAF)
- IaC: Terraform and AWS CDK (migrating off CDK)
- Data & messaging: Postgres, Redis, Kafka, OpenSearch, ClickHouse
- CI/CD: GitHub Actions
- Observability & analytics: Datadog, Sentry, Metabase
- Languages: TypeScript (Node.js), Python

## BENEFITS

- Join one of Europe's fastest-growing startups.
- Work alongside an experienced team, with backgrounds from Google, Microsoft, Oracle, Coinbase, JP Morgan, and more.
- Meaningful share options (EMI) — share in the company's success as we grow.
- Flexible hours and hybrid working — some flexibility in start and finish times, with 2 days minimum in our London office (come in more if you prefer!)
- 25 days holiday + 1 additional day per year of tenure.
- Private health insurance — including dental & optical.
- £15/day lunch budget when working from our London office, up to £180/month.
- £1,000 for your home office setup + £500/year top-up.
- Health, fitness and gift card discounts.
- Cycle2Work and Electric Cars scheme.
- Annual team offsites to sunny spots (last ones were in Croatia and Portugal ☀️)

We’re open to discussing flexible arrangements – please share any preferences in your application.

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.

## About StackOne

## Company Overview
- **One-liner**: StackOne provides integration infrastructure that connects AI agents to any SaaS system with 420+ pre-built connectors and prompt injection defense.
- **Entity Type**: Private (Series A — $24M total funding)
- **Headquarters**: Newbury, Berkshire, United Kingdom (registered office; team distributed globally across Europe and the United States)
- **Founded**: 2023
- **Founders**: Romain Sestier (Co-Founder & CEO), Guillaume Lebedel (Co-Founder & CTO)

## Core Business
- **Primary industry**: Integration infrastructure for AI agents; enterprise software connectivity
- **Target customers**: B2B developers and companies building or deploying AI agents (including off-the-shelf agents like Claude and Cursor) that need to take action across HRIS, ATS, CRM, LMS, IAM, documents, and other business applications
- **Mission or purpose**: Fuel innovation by connecting AI agents to software — let the agent think, StackOne takes action
- **Customer verticals**: Enterprise, SMB, and platform companies (customers include Drata, Attensi, Localyze)

## Products & Services
- **StackOne Platform**: Core integration infrastructure that exposes 25,000+ pre-built actions across 330+ connectors (now 420+). Handles authentication, rate limiting, retries, data transformation, and governance. Supports MCP, A2A, AI Action SDK (Python/TypeScript), and direct REST APIs.
- **StackOne Defender**: Open-source prompt injection detection library (two-tier defense: pattern matching in ~1ms + ML classifier in ~10ms) that scans tool responses before they reach the LLM. F1 score 0.87-0.88, runs in-process with no external API calls.
- **Falcon Execution Engine**: Next-generation engine that runs every agent action across REST, GraphQL, SOAP, and proprietary APIs. Handles auth, retries, errors, data transformation, and per-provider throttling.
- **Connector Builder**: Allows creation of production-ready connectors for any API (including SOAP, OData, proprietary) in minutes, declared as YAML in Git.
- **Permissions API**: Normalizes RBAC, scopes, and ACLs across all integrations into a single model with sub-millisecond checks and per-tenant scoping.
- **Audit Trail & Compliance**: Full logging of every API call, permission check, and credential use. SOC 2 Type II, GDPR, HIPAA, and CCPA compliant. Privacy-first architecture — no customer data stored by default.

## Market Standing
- **Valuation/Market Cap**: Not disclosed
- **Key Metric**: Total funding raised — $24M
  - Seed: $3.6M (Q2 2024, led by Episode 1 and Playfair; angel investment from Co-Founder of GitHub in Q2 2023)
  - Series A: $20M (May 2025, led by GV/Google Ventures, with Workday Ventures, XTX Ventures, Episode 1, Playfair, and angels from OpenAI, DeepMind, Microsoft, Mulesoft)
- **Notable Investors/Partners**: GV (Google Ventures), Workday Ventures, XTX Ventures, Episode 1, Playfair Capital
- **Growth Signals**: Surpassed 1 billion API calls; 420+ connectors and 25,000+ actions; customers across three continents; one of the fastest-growing AI agent infrastructure platforms; expanded from 20 integrations in Q4 2023 to 330+ in 2025

## Competitive Advantages
- **Privacy-first architecture**: No customer data persisted by default — proxies requests in real-time, nothing to breach.
- **Multi-protocol support**: MCP, A2A, SDKs, REST — agents connect however they want.
- **Two-tier prompt injection defense**: Open-source Defender catches threats in <4ms with 88.7% accuracy; runs in-process with no additional latency or cost.
- **Declarative connectors as code**: Every connector is a YAML file in Git — reviewable, testable, reproducible.
- **Certified compliance**: SOC 2 Type II, HIPAA, GDPR, CCPA — unlike many unification APIs.
- **Low-latency execution engine (Falcon)**: Handles rate limits, retries, and transforms data in real-time, optimized for agent context windows.

## Strategic Focus
- Continue investing in R&D for its state-of-the-art tool-calling LLM and expanding the breadth and depth of integrations.
- Scale enterprise adoption by deepening governance, permissions, and audit capabilities.
- Build out developer ecosystem (MCP servers, open-source tools) to lower friction for AI agent developers.
- Expand across new categories (IAM, messaging, documents) and increase action coverage per connector.

## Why Work Here
- **Culture & team**: Founded by a pair (CEO Romain Sestier and CTO Guillaume Lebedel) who have worked together for over a decade at Oracle, JP Morgan, Google, Microsoft, and other top tech companies. Team is distributed across Europe and the US.
- **Remote/hybrid**: Distributed team with global operations — location flexibility. Open roles include Engineering (AI, Platform, Security, UI) and GTM.
- **Growth stage**: Post-Series A ($20M from GV) — well-funded, high-growth phase with product-market fit and accelerating adoption (1B+ API calls). Opportunity to shape the infrastructure layer for the AI agent era.
- **Engineering focus**: Emphasis on security, low latency, open-source contributions (Defender), and building for developers. Stack includes modern AI/ML tooling, ONNX models, and multi-protocol systems.
- **Perks**: Competitive compensation, equity (startup), and the chance to work on the critical security/compliance layer for enterprise AI agents.

## Sources
1. [stackone.com](https://www.stackone.com/)
2. [stackone.com/company](https://www.stackone.com/company/)
3. [stackone.com/press](https://www.stackone.com/press/stackone-raises-20m-series-a-led-by-gv-google-ventures-to-reinvent-saas-and-ai-agent-integrations/)
4. [linkedin.com/company/stackonehq](https://www.linkedin.com/company/stackonehq)
5. [jobs.ashbyhq.com/stackone](https://jobs.ashbyhq.com/stackone)

## Other roles at StackOne

- [Account Executive](https://feeny.ai/job/account-executive-stackone-remote-1qrdqf8qgfa6)
- [Account Executive](https://feeny.ai/job/account-executive-stackone-london-4zkh896mv0my) — London, United Kingdom
- [Senior Engineer (AI Governance)](https://feeny.ai/job/senior-engineer-ai-governance-stackone-london-kwjtgz6gf9kx) — London, United Kingdom
- [Security Engineer](https://feeny.ai/job/security-engineer-stackone-london-zrnr121kng2g) — London, United Kingdom
- [Senior Platform Engineer](https://feeny.ai/job/senior-platform-engineer-mollie-amsterdam-jpbhbfewj47n) — Amsterdam, Netherlands
- [Senior Platform Engineer](https://feeny.ai/job/senior-platform-engineer-trust-wallet-global-sfmq2e5y6hgn) — Global
- [Senior Platform Engineer](https://feeny.ai/job/senior-platform-engineer-sprig-san-francisco-8fmv60v67se1) — San Francisco, CA
- [Senior Platform Engineer](https://feeny.ai/job/senior-platform-engineer-legora-new-york-y92m0nvpeaf8) — New York, NY
- [Senior Platform Engineer](https://feeny.ai/job/senior-platform-engineer-farsight-ai-new-york-phyddz4b5bxv) — New York, NY
- [Senior Platform Engineer](https://feeny.ai/job/senior-platform-engineer-legora-malmo-4mjk212zcfex) — Malmö, Sweden