Senior Design Engineer, StackOne
+ Employee stock option plan
1+ day a week in office
Integration infrastructure for AI agents
Open for applications
Integration infrastructure for AI agents
21-100 employees
Open for applications
+ Employee stock option plan
1+ day a week in office
21-100 employees
Company mission
To build the integration infrastructure that lets AI agents act — securely, reliably, across any system.
Role
Who you are
- 4+ yrs professional front-end engineering with a portfolio that focus on the details
- React & TypeScript at production scale; comfortable with hooks, suspense, and server components
- Deep CSS fluency (Tailwind or equivalent) and experience of modern browser APIs
- Proven track record building or migrating component libraries/design systems
- Strong performance tuning instincts: Lighthouse, Core Web Vitals, bundle analysis, code-splitting
- Familiarity with monorepo tooling (NX or Turborepo) and micro-frontend patterns
- Ability to dive into back-end code (Node, React-router, sveltekit) to remove perf bottlenecks, instrument metrics, or adjust API shape
Desirable
- Svelte, Web Components, or other framework experimentation
- Experience with auth flows (OAuth2, OpenID Connect) and secure front-end patterns
- Web Motion & animation chops
- Prior work on B2B developer tools or dashboards at seed-to-Series-B stage
What the job involves
- StackOne’s product experience is our brand. As our first dedicated UX Engineer you will be the in-house authority on taste, polish, and performance
- You will own the component library, shape our micro-frontend architecture, and ensure that every pixel, motion, and millisecond of latency makes customers feel like they’re using the best-engineered platform on the market
- 80 % Front-end craft & design systems
- 20 % API-aware performance engineering
- Collaborate with our Designer to define & steward our design system – set the visual language, build reusable primitives, and maintain libraries that power every StackOne user interfaces
- Ship pixel-perfect UIs – React (primarily) plus; own theming, performance, and thoughtful motion
- Make performance a feature – instrument Core Web Vitals, budget bundle sizes, optimise hydration patterns, and chase performance where it matters
- Provide and maintain internal tooling as well as AI rules to allow every technical team to contribute to the front-end while aligning with the best practices you will help set
- Prototype & validate – turn product ideas into interactive proofs-of-concept that help PMs and designers converge on the right solution fast
- Champion taste & detail – host design-quality critiques, stamp out visual debt, and be the go-to voice when “good enough” isn’t
Salary benchmarks
Our take
The explosion of SaaS tools has created an integration nightmare for companies. More and more B2B customers are expecting their SaaS tools to integrate with each other natively. But building and managing API connections in-house as a software vendor is time-consuming and costly, diverting teams from their core roadmap and stopping sales teams from selling.
As the next-generation integration platform, StackOne is solving the challenge of building SaaS integrations at scale once and for all. Founded in 2023 by ex-Google and Oracle executives, StackOne has seen exceptionally fast growth since its launch. With its best-in-class security and real-time architecture, the company is well-positioned to become a category leader in the API integration solutions market.
Steph
Company Specialist at Welcome to the Jungle
Company
Funding (last 2 of 3 rounds)
Apr 2025
$20m
Series A
Nov 2023
$3.6m
Seed
Total funding: $23.9m
Company benefits
- Meaningful share options (EMI) - share in the company's success as we grow
- 25 days holiday + 1 additional day per year of tenure
- Hybrid working friendly - typically 2 days/week in our London office. We’re open to discussing flexible arrangements—please share any preferences in your application
- 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
- Health, fitness and gift card discounts
- Cycle2Work and Electric Car Scheme
- Monthly in-person socials
- Annual team offsite to sunny spots (last ones were in Spain and Portugal!)
Company HQ
Central London
Articles
Leadership
Romain Sestier
(Co-Founder & CEO)Previously worked for Google as co-founder and Product Lead of Area120, VP of Product and Sales at Yieldify, co-founder and CEO of Upper.ai and Head of UK Professional Services at ContentSquare.
Guillaume Lebedel
(Co-Founder & CTO)Previously VP of Engineering at Yieldify until its acquisition by Epsilon/Publicis. Also co-founded another start-up and worked at Maxymiser (acq. by Oracle) as a developer.
Diversity, Equity & Inclusion at StackOne
Yasmin Chalmers (Head of People)
- Women @ StackOne community
Share this job
View 2 more jobs at StackOne