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Salary: USD 320,000 - 405,000 / annual
The Encodings Infra team at Anthropic maintains the libraries that engineers and researchers use to encode text and multimodal data into a form that Claude can consume. This role also shapes Claude's prompt structure: how user turns are represented to the model, how Claude calls tools and receives results, and related infrastructure.
As a Software Engineer on this team, you will own the design and maintenance of these libraries—keeping their APIs intuitive, performance sharp, and abstractions solid enough that most of the organization never has to think about encodings or prompt structures. Your work will enable Claude to learn new ways of understanding the world.
This role is unusually broad. Your work will touch systems across the codebase, from pretraining to finetuning to the API. You will collaborate closely with both researchers and engineers to ensure new encoding ideas move quickly from experiment to production.
Key Responsibilities:
- Maintain and improve the encoding libraries used by engineers and researchers across Anthropic
- Run experiments to determine the optimal way to feed structured data into Claude
- Design data structures and abstractions that shield most of the organization from encoding details while enabling power users
- Adapt encoding libraries to support new research directions and ensure research ideas ship to production
- Optimize encoding performance across dependent systems
You may be a good fit if you have strong communication skills, enjoy working closely with researchers and engineers, are results-oriented with a bias toward flexibility and impact, and care about the societal implications of your work. The role requires picking up slack even when it goes outside your job description.
Representative projects include working with research teams to ship new multimodal data types (audio, video, etc.) to production and redesigning core abstractions to change how data is encoded into Claude without breaking downstream teams.
Location-based hybrid policy: Currently, all staff are expected to be in one of Anthropic's offices at least 25% of the time, though some roles may require more time in office. Visa sponsorship is available.
Requirements:
- 5+ years of software engineering experience with meaningful time spent maintaining libraries, SDKs, or developer-facing APIs
- Familiarity with ML terminology and LLM architecture (not required to be an ML expert, but enough understanding to work effectively alongside researchers)
- Experience carrying out complex refactors in large codebases
- Bachelor's degree or equivalent combination of education, training, and/or experience in a field relevant to the role
Strong candidates may also have experience with tokenizers or other text/data encoding systems, maintaining widely-used libraries over long periods, performance optimization, Python and/or Rust, and reinforcement learning or model training infrastructure.
