Model Performance Software Engineer (Claude Code)

Anthropic; York and North Yorkshire; On-site; GBP 100,000 - 140,000; Full time

Benefits offered by this job

Health insurance

Equity packages

Relocation support

Education stipend

Job summary

Anthropic is seeking a Staff Software Engineer for the Claude Code team in the United Kingdom. You will set technical direction at the intersection of engineering and research, architecting evaluation and research infrastructure and leading end-to-end ownership of critical systems.

You will mentor engineers, translate research questions into durable engineering solutions, and partner with research leads to shape capabilities and progress metrics while maintaining high standards of reliability

Qualifications

• Senior individual contributor with 10+ years of software engineering experience.
• Experience operating as a Staff or Principal engineer at a high-caliber organization.
• Strong correctness and reliability focus; raised engineering standards on teams.

Responsibilities

• Set technical direction for evaluation systems, research infrastructure, and internal tooling for the Claude Code team.
• Architect eval frameworks to measure model capabilities across coding tasks and scale with the roadmap.
• Lead design of infrastructure enabling researchers to run experiments at scale and make long-term tradeoffs.
• Mentor engineers, review designs, unblock peers, and model engineering standards at scale.
• Own critical systems end-to-end from architecture through production reliability.

Skills

Python

TypeScript

Engineering leadership

Job description

• We’re looking for a Staff Software Engineer to set technical direction at the intersection of engineering and research on the Claude Code team. In this role, you’ll partner directly with Anthropic’s researchers and engineering leadership to shape how we measure, understand, and improve Claude’s coding capabilities
• You’ll architect the systems, tooling, and evaluation infrastructure that determine how quickly our research can move—and you’ll be accountable for the technical decisions that ripple across the team and beyond
• Set technical direction for evaluation systems, research infrastructure, and internal tooling across the Claude Code team
• Architect eval frameworks that measure model capabilities across diverse coding tasks and scale with our research roadmap
• Lead the design of infrastructure that enables researchers to run experiments at scale, and make the foundational tradeoffs that shape how the team operates for years
• Identify the highest-leverage engineering investments—often before anyone has asked for them—and drive them to completion
• Serve as a senior technical bridge between product and research, using strong product intuition to influence which capabilities we prioritize and how we measure progress against them
• Mentor and raise the bar for other engineers on the team; review designs, unblock peers, and model the engineering standards we want to scale
• Partner with research leads to translate ambiguous research questions into durable engineering solutions
• Own critical systems end-to-end, from architecture through production reliability, and take responsibility for their long-term health

Benefits

• Comprehensive health, dental, and vision insurance for you and your dependents
• Inclusive fertility benefits via Carrot Fertility
• 22 weeks of paid parental leave
• Flexible paid time off and absence policies
• Mental health support for you and your dependents
• Competitive salary and equity packages
• Optional equity donation matching at a 1:1 ratio, up to 25% of your equity grant
• Retirement plans with competitive matching
• Life and income protection plans
• $500/month flexible wellness and time saver stipend
• Commuter benefits
• Annual education stipend
• Home office stipends
• Relocation support for those moving for Anthropic
• Daily meals and snacks in the office

This is a senior individual contributor role for someone who has already built and owned systems at significant scale, and who is ready to operate as a technical leader: driving architecture, mentoring engineers, and influencing the direction of Claude Code itselfCan dive into unfamiliar technical domains—ML systems, research workflows, novel infrastructure—get to the frontier quicklyTake full ownership of ambiguous, open-ended problems and drive them to completion with minimal directionHave 10+ years of software engineering experience, with a track record of operating as a Staff or Principal engineer (or equivalent) at a high-caliber organizationCare deeply about correctness and reliability, and have raised engineering standards on teams you’ve been part ofAre a power user of agentic coding tools with deep intuition about model capabilities and limitationsAre energized by working at the boundary between engineering and AI research, and by the prospect of influencing bothHave architected and owned complex, high-stakes systems—pipelines, infrastructure, or platforms that orchestrate many components, handle significant state and logic, and serve multiple teamsThrive in high-intensity environments with fast iteration cycles, and have the judgment to know when to move fast and when to invest in durabilityHave a history of setting technical direction that others follow—through design docs, architectural decisions, or technical strategy that shaped how a team or org operatesReinforcement learning infrastructure or training systemsDesigning or scaling eval/evaluation frameworks for ML systemsLeading technical initiatives in high-performance, demanding environments—trading firms, quant funds, frontier research labs, or fast-moving startups where intensity and technical excellence are the normResearch computing, scientific infrastructure, or developer platforms at scaleExpertise in Python and TypeScriptA strong quantitative foundation (math, physics, or related fields)