At a Glance
- Tasks: Build and ship innovative features across frontend, backend, and infrastructure.
- Company: Join StackOne, a fast-growing startup revolutionising SaaS integrations with AI.
- Benefits: Enjoy meaningful share options, private health insurance, and a generous holiday allowance.
- Other info: Work hybrid with a vibrant team of industry veterans and enjoy annual team offsites.
- Why this job: Be part of a dynamic team pushing the boundaries of technology in a collaborative environment.
- Qualifications: Experience in full-stack development, TypeScript, and React is essential.
The predicted salary is between 36000 - 60000 £ per year.
About StackOne: StackOne is the AI Integration Gateway for SaaS products and AI Agents. Backed by GV and Workday Ventures ($24M raised), we help builders of SaaS platforms and AI Agents orchestrate hundreds of scalable, accurate, and enterprise-grade integrations. Our platform combines 25,000 pre-mapped actions on 200 connectors, an AI-powered integration development toolkit, plus security by design: a real-time architecture, managed authentication and permissions, and end-to-end observability.
Join us on our fast trajectory to build the future of agentic integrations. With an AI-native integration toolkit that delivers real-time execution, managed authentication, granular permissions, and full observability, all built with safety at its core, we're now doubling down on AI R&D & creating our own lab to push the boundaries of tool calling for agents: training specialized LLMs designed to outperform general-purpose models in what matters most: precision, reliability, and safety in agentic execution.
About the role: We're looking for full-stack engineers who can ship fast, think in systems, and obsess over scalability, performance & usability. You'll build core APIs, scale infra, and ship dev tools & UIs that make tool execution easy, safe and predictable. It's a broad role: backend-heavy, product-aware, and deeply technical. Expect to work across APIs, auth, infra, and frontend, building the foundation that lets agents take real action.
Responsibilities:
- Act as a full-stack web application engineering: ideate, build, and ship features across frontend, backend, data, and infrastructure.
- Model data & schemas across SQL, document/columnar stores, and OLAP; design for correctness, performance, and cost.
- Design and evolve public APIs and standards: REST contracts, OpenAPI, pagination, auth, error models, plus MCP/tool-calling conventions.
- Engineer for scale and resilience: rate limiting, retries, idempotency, back-pressure, caching, SLIs/SLOs, and safe fallbacks.
- Build and operate event systems with Kafka-class streaming patterns: producers/consumers, partitioning, DLQs, reprocessing, schema evolution.
- Raise observability & reliability: tracing, metrics, logs, alerting, zero-downtime deploys, runbooks.
- Leverage LLMs/agents to accelerate development while maintaining reliability, testing, and code quality.
What we're looking for:
- Proven experience as a full-stack engineer shipping user-facing, backend-heavy systems.
- Expertise in TypeScript and solid experience with React; comfortable building clean UIs for complex backend capabilities.
- Strong background designing and operating public APIs and multi-tenant systems.
- Experience with distributed systems concepts: streams, queues, idempotency, consistency, and performance trade-offs.
- Ability to think in systems (throughput, tail latency, failure modes) and explain trade-offs clearly.
- Curiosity and pragmatism with LLMs/agents: know when they help, and how to guardrail/evaluate them.
- Desire to work in a fast-paced startup, take ownership end-to-end, and bias toward shipping.
- (Preferred) Experience publishing CLIs & SDKs (internal or open-source).
Our Stack: You will have a lot of freedom and agency to choose 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
Benefits:
- Meaningful share options (EMI) - share in the company's success as we grow
- 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 £120/month
- £1,000 for your home office set up + £500/year top-up
- 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
- Health, fitness and gift card discounts
- Cycle2Work and Electric Cars scheme
- Hybrid work set up - typically 2 days 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.
Product Engineer in London employer: StackOne
StackOne is an exceptional employer, offering a dynamic work culture that fosters innovation and collaboration among a team of seasoned professionals from top tech companies. With meaningful share options, generous holiday allowances, and a hybrid work setup, employees enjoy a balanced work-life experience while contributing to cutting-edge AI integration solutions in the heart of London. The company prioritises employee growth through continuous learning opportunities and a supportive environment, making it an ideal place for those looking to make a significant impact in the tech industry.
StudySmarter Expert Advice🤫
We think this is how you could land Product Engineer in London
✨Tip Number 1
Network like a pro! Reach out to folks in your industry on LinkedIn or at meetups. A friendly chat can open doors that a CV just can't.
✨Tip Number 2
Show off your skills! Create a portfolio or GitHub repo showcasing your projects. When you apply through our website, link it up to give us a taste of what you can do.
✨Tip Number 3
Prepare for the interview like it's a big game! Research StackOne, understand our tech stack, and think about how your experience aligns with our mission. We love candidates who are genuinely excited about what we do.
✨Tip Number 4
Follow up after your interview! A quick thank-you note can leave a lasting impression. It shows you're keen and professional, which is exactly what we look for at StackOne.
We think you need these skills to ace Product Engineer in London
Some tips for your application 🫡
Tailor Your Application:Make sure to customise your CV and cover letter for the Product Engineer role. Highlight your experience with full-stack development, especially in TypeScript and React, and show how your skills align with our mission at StackOne.
Showcase Your Projects:Include links to any relevant projects or GitHub repositories that demonstrate your expertise in building user-facing systems and APIs. We love seeing practical examples of your work!
Be Clear and Concise:When writing your application, keep it straightforward and to the point. Use clear language to explain your experience and how it relates to the responsibilities outlined in the job description.
Apply Through Our Website:We encourage you to apply directly through our website. It’s the best way for us to receive your application and ensures you’re considered for the role. Plus, it shows you’re keen on joining our team!
How to prepare for a job interview at StackOne
✨Know Your Tech Stack
Familiarise yourself with the technologies mentioned in the job description, especially TypeScript, React, and AWS. Be ready to discuss your experience with these tools and how you've used them in past projects.
✨Demonstrate System Thinking
Prepare to explain how you approach system design and performance trade-offs. Think about examples where you've had to make decisions regarding scalability and reliability, and be ready to share those insights during the interview.
✨Showcase Your API Knowledge
Since the role involves designing public APIs, brush up on REST contracts and OpenAPI specifications. Be prepared to discuss your experience with API development and any challenges you've faced in ensuring their usability and performance.
✨Emphasise Your Curiosity
The company values curiosity, especially regarding LLMs and agents. Share your thoughts on how these technologies can enhance development processes and how you've evaluated their effectiveness in your previous work.
