Software Engineering • Mid-Level

About the role:

Claude.ai is Anthropic's flagship consumer product, spanning web, mobile, desktop, and browser extensions—and it's growing fast. The UI Platform team owns the foundational layer that makes all of this possible: the shared infrastructure, components, APIs, and tooling that let every other product team at Anthropic ship quickly, reliably, and with confidence.

As a Software Engineer on this team, you'll be hands-on building the platform that other engineers depend on every day. This means designing and shipping shared components and design-system-level abstractions, evolving the backend-for-frontend (BFF) APIs that power our client applications, and improving the build, deploy, and observability systems that keep Claude.ai running smoothly across surfaces. Your work will directly shape how fast teams across Anthropic can innovate—and how stable their experiences are when they do.

This is a great fit if you care deeply about developer experience and want your engineering work to have outsized leverage: instead of shipping one feature, you're building the tools and systems that make dozens of features possible.

Responsibilities:

• Design and build shared UI components, libraries, and abstractions that product teams across Anthropic use to ship consistently and efficiently on web and mobile
• Contribute to the BFF API layer that powers Claude.ai's client applications—thinking carefully about clean contracts, performance, and reliability at the boundary between frontend and backend
• Improve developer velocity across the organization by reducing friction in our build, deploy, and testing pipelines
• Work on performance and reliability: identify and resolve latency issues, improve observability, and help establish high standards that the rest of the platform team can build on
• Partner closely with product engineering teams to understand their needs, unblock them when possible, and shape platform investments around where the most impact is
• Help maintain and evolve documentation and tooling that make the platform approachable for engineers joining or building on top of it

You may be a good fit if you:

• Have 5+ years of software engineering experience, with significant time spent building shared platforms, developer tools, or infrastructure that other engineers rely on
• Have strong practical skills in modern web technologies (React, TypeScript, Next.js) and experience designing or consuming APIs that serve frontend applications
• Care about developer experience and have a track record of building things that make other engineers more productive
• Have solid instincts around reliability, observability, and performance—and enjoy operationalizing those instincts in production systems
• Thrive in fast-paced, collaborative environments and enjoy working closely with cross-functional partners
• Pick up slack, even if it goes outside your job description

Strong candidates may also have experience with:

• Building shared component libraries or design systems for multiple surfaces (web, mobile, desktop)
• BFF architectures and API patterns that balance flexibility with consistency across client platforms
• Performance optimization and latency reduction in consumer-facing applications
• CI/CD, build systems, and deployment automation
• Observability and monitoring (metrics, logging, tracing)
• Working on AI/ML products or in rapidly evolving product environments

Candidates need not have:

• 100% of the skills needed to perform the job
• Formal certifications or education credentials