Mid-career | AI Harness Engineer (Fixstars)English summary from Japanese

FIXSTARS GROUP

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Salary

600～1010万円 ※スキル・ご経験により応相談

Location

株式会社フィックスターズ本社東京都港区芝浦1-1-1 BLUE FRONT SHIBAURA TOWER S 31階【就業場所の変更の範囲】会社の定める場所（配置転換、出向、転籍の可能性あり）

Job Type

Full-time

Work Style

裁量労働制適用所定労働時間：8時間 (推奨：始業時間10:00、終業時間19:00) 休憩時間：1時間 ※専門業務型裁量労働制により9時間働いたものとみなします完全週休2日制(土・日・祝日) 、夏季休暇、年末年始休暇

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Role summaryEnglish summary from Japanese

English summary for screening — check the original posting before applying.

Fixstars is seeking an AI Harness Engineer to develop a system that autonomously executes performance engineering for applications requiring multiple servers, such as LLMs and large-scale AI. The role involves reconstructing Fixstars' 20+ years of performance engineering expertise into an AI agent "harness" and integrating it into the AI Native software development environment, Fixstars Vega.

Must-haves

Experience with AI Native software development processes
Experience investigating performance bottlenecks using profilers (e.g., PyTorch Profiler, NVIDIA Nsight Systems) and implementing actual speedups
Programming experience in Python or C/C++

Nice-to-haves

Knowledge/experience with ML compilers or machine learning toolchains/services like quantizers
Basic knowledge and environment setup experience with LLMOps

Tech stack

UbuntuPython 3C/C++GitGitLabDockerSlackFixstars Vega

Work style

Hybrid (up to 2 days remote per week), Onsite at Fixstars HQ in Tokyo

Other notes

Salary: 6,000,000 - 10,100,000 JPY (negotiable based on skills/experience). Includes various allowances and bonuses. Discretionary labor system applies.

About the Company

FIXSTARS GROUP

Headquarters

東京都港区芝浦1-1-1 BLUE FRONT SHIBAURA TOWER S 31階

Founded

2002-08

Visit Website

Posted8/3/2026

Updated2026/08/03 10:29

Sourceherp