Backend & Cloud Engineer

**About the company:** 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. **Responsibilities:** You’ll have a wide range of responsibilities across our cloud infrastructure and product backend. On the cloud infrastructure side, you’ll work on latency and cost optimization, scalability, monitoring, and deployments. On the product side, you’ll work with web servers, SQL databases, LLM/AI libraries, GPU inference, API design, integrating with external services (e.g. SSO), and general product functionality to govern AI models and agents. Requirements 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 5 years of experience in cloud infrastructure and/or backend engineering. We don’t require experience in GCP or Python specifically, but we expect you to be an expert in the cloud platform or technical stack of your choice. Business-level English and Japanese are required. We prioritize candidates in Tokyo, but may consider remote for exceptional candidates. Nice to haves While not specifically required, tell us if you have any of the following. You’ve worked at a startup before, or you have AI/ML/LLM experience. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION 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 Read more More jobs like this We'll send you a digest of new English-friendly software developer jobs in Japan. Your email stays private, we don't share or sell it. Apply for this position × This position is only open to current residents of Japan. This position requires business Japanese. I have a favour to ask. When you apply to Citadel AI, please tell them that you heard about the position on TokyoDev . This helps to keep this job board sustainable, so I'd be grateful for your support with this. - Paul, Founder of TokyoDev Continue applying © 2026 Privacy Policy **Requirements:** 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 5 years of experience in cloud infrastructure and/or backend engineering. We don’t require experience in GCP or Python specifically, but we expect you to be an expert in the cloud platform or technical stack of your choice. Business-level English and Japanese are required. We prioritize candidates in Tokyo, but may consider remote for exceptional candidates. **Nice to have:** While not specifically required, tell us if you have any of the following. You’ve worked at a startup before, or you have AI/ML/LLM experience. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION 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 Read more More jobs like this We'll send you a digest of new English-friendly software developer jobs in Japan. Your email stays private, we don't share or sell it. Apply for this position × This position is only open to current residents of Japan. This position requires business Japanese. I have a favour to ask. When you apply to Citadel AI, please tell them that you heard about the position on TokyoDev . This helps to keep this job board sustainable, so I'd be grateful for your support with this. - Paul, Founder of TokyoDev Continue applying © 2026 Privacy Policy