Used Tools & Technologies
Not specified
Required Skills & Competences
Tag name is followed by "@" symbol and proficiency level value.
About proficiency levels:
- 1-2 — basic awareness. Minimal hands-on experience, and a rudimentary understanding of the technology's purpose;
- 3-6 — daily use. Comfortable and regular usage, capable of handling common tasks and challenges related to the technology;
- 7-9 — you are an expert, you can teach others, you know all the pitfalls and tricks;
- 10 — exceptional knowledge, comprehensive understanding, and adeptness in all aspects of the technology, including advanced problem-solving. Think twice before claiming or demanding such level.
Linux @ 6
Communication @ 3
JavaScript @ 3
Rust @ 3
Claude Code @ 3
AI @ 3
Profiling @ 3
- 1-2 — basic awareness. Minimal hands-on experience, and a rudimentary understanding of the technology's purpose;
- 3-6 — daily use. Comfortable and regular usage, capable of handling common tasks and challenges related to the technology;
- 7-9 — you are an expert, you can teach others, you know all the pitfalls and tricks;
- 10 — exceptional knowledge, comprehensive understanding, and adeptness in all aspects of the technology, including advanced problem-solving. Think twice before claiming or demanding such level.
Details
Anthropic is building reliable, interpretable, and steerable AI systems. This role is a systems-oriented software engineering position focused on pushing the performance and reliability of Claude Code and the JavaScript runtime that powers it (Bun). You'll work deep in the runtime, the kernel interfaces it sits on top of, and the agent execution loop, improving memory usage, latency, and startup time. This is low-level systems work that involves production C/C++ and Rust, thinking in syscalls and allocators, and shaving microseconds and megabytes off hot paths.
Responsibilities
- Design, build, and optimize core systems inside Bun and Claude Code — runtime internals, I/O paths, memory management, and the agent execution loop
- Drive down memory usage, latency, and startup time across Claude Code and the Bun runtime
- Dig into performance problems across the stack: profiling, tracing, and fixing issues anywhere from the kernel interface up through the JS engine to the agent layer
- Collaborate with researchers and product engineers to translate model capabilities into a fast, reliable developer experience
- Contribute to the Bun runtime and toolkit that underpins Claude Code, the Agent SDK, Cowork, and other internal Labs products
- Stay ahead of advancements in runtimes, compilers, and AI-assisted tooling — experiment, measure, and bring the best ideas into the stack
Requirements
- Strong background in C and/or C++ and Rust (Zig also welcome)
- Deep systems programming experience: syscalls, Linux internals, I/O (kqueue, epoll, io_uring), manual memory management, and performance engineering
- Experience working on language runtimes, virtual machines, compilers, or JS engines (for example JavaScriptCore or SpiderMonkey)
- Proficiency with profiling and tracing to identify and fix performance issues across kernel interfaces, JS engines, and agent layers
- 5+ years of professional work experience
- Minimum education: Bachelor’s degree or equivalent combination of education, training, and/or experience
Logistics
- Annual salary range: $320,000 - $485,000 USD
- Location: San Francisco, CA; location-based hybrid policy (expectation to be in one of our offices at least ~25% of the time)
- Visa sponsorship: Anthropic sponsors visas and retains an immigration lawyer; they will make reasonable efforts to obtain a visa for hired candidates (though not every role/candidate can be successfully sponsored)
How we work / Culture
- Anthropic values collaboration across research, engineering, policy, and business teams, and emphasizes communication skills
- The team conducts frequent research discussions and works on large-scale research efforts with an emphasis on safety and societal benefit
Benefits
- Competitive compensation and benefits
- Optional equity donation matching
- Generous vacation and parental leave
- Flexible working hours and a collaborative office space in San Francisco