This position is closed and is no longer accepting applications.

Backend Engineer

Citadel AI Shibuya-ku, Tokyo
  • 💴 No salary range given
  • 🏡 Partially remote
  • 🧪 1+ years experience required
  • 💬 No Japanese required
  • 🌏 Apply from abroad
  • 🧳 Relocate to Japan

About Citadel AI

Citadel AI Shibuya-ku, Tokyo

Citadel AI builds products to test and monitor high-risk AI systems. Our mission is to make the world's AI systems more reliable and trustworthy.

Key benefits

  • International team and global customers
  • World-class engineering team
  • Significant ownership and impact

About the position

We’re hiring backend engineers to work with our small, full-stack team to build products to test, monitor, and improve the reliability of machine learning systems.


You’ll be responsible for building our product’s backend and working with web servers, SQL databases, parallel computing, API design, multi-cloud architecture, integrating with external services (e.g. SSO), and going as deep into our ML stack as you can.

Our backend is primarily in Python. Some technologies we use are: Docker, PostgreSQL, Redis, RQ, Gunicorn, Flask, TensorFlow Extended, Pytest, and many Python ML libraries.


No ML expertise is required for this role, though we hope you’re interested to dive deep into the emerging space of MLOps / trustworthy ML / responsible AI.

Our company, technology, and market are new and changing rapidly, so a large part of the job is to adapt and learn new things. We value learning fast over pre-existing knowledge (“slope is more important than y-intercept”).

You should have at least 1 year of backend software engineering experience. We don’t require past experience with specific programming languages or frameworks.

We prioritize candidates in Tokyo, but may consider remote for exceptional candidates.

Nice to haves

These aren’t required, but be sure to mention them in your application if you have them.

You can work full-stack, you’ve worked at a startup before, or you have experience with production machine learning.


As an early employee, you’ll own a significant equity stake in addition to your base salary.

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