Fullstack Engineer (Frontend focus) in London

CoreWeave is The Essential Cloud for AI™. Built for pioneers by pioneers, CoreWeave delivers a platform of technology, tools, and teams that enables innovators to build and scale AI with confidence. Trusted by leading AI labs, startups, and global enterprises, CoreWeave combines superior infrastructure performance with deep technical expertise to accelerate breakthroughs and turn compute into capability.

What You’ll Do: The Monolith AI Engineering Team at CoreWeave is responsible for building and scaling the core platform that powers the world’s most advanced engineering simulation and AI workflows — our ambition is to become the super‑intelligent AI test lab for the engineering industry, helping customers “ship science, faster.” From evolving distributed architecture to enabling the next generation of agentic interfaces and physical AI, this team delivers the performant, reliable, and scalable foundation trusted by the world’s largest engineering companies. The Fullstack Engineer (Frontend Focus) will own and evolve the Monolith platform’s product surface — the data‑heavy, workflow‑centric web experience where engineers design experiments, compare runs, interact with agents, and turn complex physical test data into decisions. You’ll partner closely with Design, Product, and Backend Engineering to ship UI and UX that feel fast, intuitive, and trustworthy for non‑ML expert engineers, while also contributing to our Python backend services when needed.

About the Role: We’re targeting an IC5 Fullstack Staff Engineer with a strong frontend background, and are also open to exceptional Senior Fullstack Engineer II (IC4) candidates who can operate at staff‑like scope. The role is heavily frontend‑weighted (roughly 80–90%), focused on owning the Monolith web application: component architecture, design system evolution, performance, and UX for complex, data‑rich workflows. You’ll also work across our Python services (FastAPI/Flask) to shape and integrate APIs, bring new platform capabilities to the UI, and occasionally deliver backend features that unlock better user experiences. You’ll be a key partner in defining how engineers experience Monolith’s “AI test lab” — from agent chat to experiment exploration and monitoring — and will help set the bar for frontend quality, reliability, and developer experience across the team.

In this role, you will:

• Frontend Ownership & Experience: Own significant areas of the Monolith frontend, from architecture and component design to implementation, refactors, and ongoing maintenance. Design and build modern, responsive UIs using React and TypeScript, with a focus on complex, data‑heavy views (tables, charts, experiment timelines, dashboards, agents) that remain fast and understandable for users. Collaborate with Design to evolve our design system and component library, ensuring consistency, accessibility, and a high‑quality visual language across the product. Drive frontend performance improvements (bundle size, rendering strategies, network usage) to keep the app responsive even under large datasets and long‑running workflows. Champion accessibility and usability, ensuring the interface works well for time‑pressed engineers in demanding environments.
• Fullstack Development & Platform Integration: Work closely with backend engineers on our Python services to design clean API contracts, shape data models for UI needs, and debug issues across the stack. Implement and integrate backend functionality (primarily in Python) when it materially improves UX or unlocks new workflows, including occasional work on API endpoints, background tasks, and data transformations. Collaborate with our agent and platform teams to expose agentic capabilities (e.g. platform agent) safely and intuitively in the frontend experience. Contribute to fullstack observability — instrumenting both frontend and backend for metrics, logging, and tracing, and using that data to guide product and performance improvements.
• Collaboration, Quality & Developer Experience: Work hand‑in‑hand with Product and Design to scope projects, define success criteria, and break down ambiguous problems into iterative deliverables. Maintain a high bar for code quality through thoughtful design, code reviews, tests (unit, integration, and E2E), and documentation. Help improve our frontend developer experience — build tooling, workflows, and patterns that make it easier for the team to ship reliable UI quickly (Storybook/design‑system improvements, local dev ergonomics, CI checks, etc.). Mentor other engineers on frontend best practices, UX thinking, and effective fullstack collaboration.

Who You Are:

• Experience & Level: Typically 7+ years of professional software engineering experience, including substantial time building and maintaining complex, user‑facing web applications as a fullstack or frontend‑leaning engineer. A track record of operating at Senior/Staff scope: owning significant product surface area, driving cross‑team projects, and making architectural decisions that last.
• Frontend Expertise: Advanced proficiency in React and TypeScript, with experience structuring large‑scale frontends (modules, state management, routing, data‑fetching patterns). Strong command of web fundamentals. Experience building data‑heavy and visualization‑centric UIs — e.g. dashboards, charts, time‑series visualizations, experiment or metrics explorers. Familiarity with design systems and component libraries (Storybook or similar), and an eye for when design details materially impact user trust and productivity.
• Backend & Platform Skills: Solid experience with Python in production environments (FastAPI, Flask, or Django), including building and integrating REST or GraphQL APIs that power frontend experiences. Comfortable working in service‑oriented or microservice architectures, reasoning about data flows, failure modes, and performance across boundaries. Experience with SQL databases (e.g. PostgreSQL) and practical data modelling for product features. Familiarity with modern cloud and container stacks (Docker, Kubernetes, and at least one major cloud provider).
• Quality & Ways of Working: Strong habits around testing (unit, integration, and E2E) and CI/CD for frontend and backend changes. Effective collaborator with Product, Design, and cross‑functional stakeholders; clear written and verbal communicator who can explain trade‑offs and constraints. Comfortable working in a fast‑moving, high‑ambiguity environment where we balance shipping quickly with maintaining a reliable platform.

Preferred:

• Experience building UIs for technical or data‑savvy users (ML engineers, data scientists, physical test engineers, or similar), especially in B2B SaaS products.
• Familiarity with GraphQL and typed API clients in React (or strong REST plus a desire to pick up GraphQL quickly).
• Experience with SSR/SSG frameworks, particularly for performance‑sensitive dashboards.
• Prior work with time‑series and experiment tracking tooling, ML platforms, or analytics products.
• Exposure to ML/AI workflows (experiments, training runs, evaluations, agents) and interest in “tools for AI engineers” as a product domain.
• Experience with frontend observability (Sentry, Datadog, OpenTelemetry, etc.) and using telemetry to guide UX improvements.

Wondering if you’re a good fit? We believe in investing in our people, and value candidates who can bring their own diversified experiences to our teams — even if you aren’t a 100% skill or experience match. Here are a few qualities we’ve found compatible with our team. If some of this describes you, we’d love to talk.

• Product‑minded craftsperson – you care as much about the user experience and clarity of a workflow as you do about the quality of the code behind it.
• Detail‑oriented on complex UX – you enjoy making intricate, data‑heavy interfaces feel simple and intuitive, and you’re willing to sweat the small interactions to get there.
• Pragmatic and velocity‑driven – you know when to build the perfect abstraction and when to ship a well‑engineered, incremental improvement that moves the product forward.
• Collaborative and empathetic – you build strong relationships with engineers, designers, and PMs, and you’re comfortable iterating based on feedback from customers and colleagues.
• Owner’s mindset – you feel responsible for the experience end‑to‑end, follow through on problems across the stack, and care deeply about the impact your work has on customers and the business.

Why CoreWeave? At CoreWeave, we work hard, have fun, and move fast! We’re in an exciting stage of hyper‑growth that you will not want to miss out on. We’re not afraid of a little chaos, and we’re constantly learning. Our team cares deeply about how we build our product and how we work together, which is represented through our core values:

• Be Curious at Your Core
• Act Like an Owner
• Empower Employees
• Deliver Best‑in‑Class Client Experiences
• Achieve More Together

We support and encourage an entrepreneurial outlook and independent thinking. We foster an environment that encourages collaboration and enables the development of innovative solutions to complex problems. As we get set for takeoff, the organization’s growth opportunities are constantly expanding. You will be surrounded by some of the best talent in the industry, who will want to learn from you, too. Come join us!

To fulfil our obligation to protect client data, successful applicants offered employment with CoreWeave will be required to complete a basic criminal record check, conducted in compliance with GDPR. Employment offers are conditional upon receiving satisfactory check results.

What We Offer: In addition to a competitive salary, we offer a variety of benefits to support your needs, including:

• Family-level Medical Insurance
• Family-level Dental Insurance
• Generous Pension Contribution
• Life Assurance at 4x Salary
• Critical Illness Cover
• Employee Assistance Programme
• Tuition Reimbursement
• Work culture focused on innovative disruption

Benefits may vary by location.

Our Workplace: While we prioritize a hybrid work environment, remote work may be considered for candidates located more than 30 miles from an office, based on role requirements for specialized skill sets. New hires will be invited to attend onboarding at one of our hubs within their first month. Teams also gather quarterly to support collaboration.

CoreWeave is an equal opportunity employer, committed to fostering an inclusive and supportive workplace. All qualified applicants and candidates will receive consideration for employment without regard to race, color, religion, sex, disability, age, sexual orientation, gender identity, national origin, veteran status, or genetic information.