Software Engineer, Tokens and Prompt Structures (AI)

Location: San Francisco, CA or New York City, NY; hybrid policy requiring staff to work from an office at least 25% of the time

Annual salary: $320,000–$405,000 USD

Company

Anthropic develops reliable, interpretable, and steerable AI systems intended to be safe and beneficial for users and society.

What you will do

• Maintain and improve encoding libraries used by engineers and researchers.
• Run experiments to determine effective ways to feed structured data into Claude.
• Design data structures and abstractions that simplify encoded-data workflows while supporting advanced users.
• Adapt encoding libraries for new research directions and move research ideas into production.
• Optimize encoding performance across dependent systems.
• Collaborate with researchers and engineers across pretraining, finetuning, and the API.

Requirements

• 5+ years of software engineering experience, including meaningful experience maintaining libraries, SDKs, or developer-facing APIs.
• Familiarity with machine learning terminology and LLM architecture.
• Experience performing complex refactors in large codebases.
• Strong communication skills and effective collaboration with researchers and engineers.
• Bachelor’s degree or equivalent education, training, or professional experience in a relevant field.
• Ability to work under the location-based hybrid policy in San Francisco or New York City.

Nice to have

• Experience with tokenizers or other text and data encoding systems.
• Long-term maintenance of a widely used library.
• Performance optimization experience.
• Python or Rust experience.
• Experience with reinforcement learning or model training infrastructure.

Culture & Benefits

• Collaborative work across research, engineering, policy, and business disciplines.
• Focus on large-scale AI research and steerable, trustworthy AI.
• Flexible working hours and an office environment for collaboration.
• Generous vacation and parental leave.
• Competitive compensation and optional equity donation matching.
• Visa sponsorship is available, with immigration-lawyer support, subject to role and candidate eligibility.

Hiring process

• Applicants may use AI during the application process according to Anthropic’s candidate AI usage policy.