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Software Engineer, Tokens and Prompt Structures

San Francisco, CA💼 Full-time💰 $320,000–$320,000🗓 2026-09-16 → 2026-09-26

Core

Design and maintain encoding libraries and prompt structures that enable Claude to consume text and multimodal data, bridging research experiments to production systems.

Role type

Senior Software Engineer (LLM Infrastructure & Encoding)

Builds

Core encoding libraries, SDKs, and data abstractions used across Anthropic's pretraining, finetuning, and API systems.

Domain

Artificial Intelligence / Large Language Models / Data Encoding

Deliverable

production ML models | product features

Required skills

Software engineering, library/SDK/API design, complex refactoring, ML/LLM architecture understanding, performance optimization

Preferred skills

Tokenizer experience, long-term library maintenance, Python, Rust, reinforcement learning infrastructure

Technologies

Python, Rust

Responsibilities

Maintain and improve encoding libraries used by engineers and researchers; Run experiments to optimize structured data feeding into Claude; Design data structures and abstractions to shield the organization from encoding details; Adapt libraries to support new research directions and ship to production; Optimize encoding performance across dependent systems

Seniority

Senior, hands-on IC

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