Frontend Engineer

Citadel AI Shibuya-ku, Tokyo April 3 2026
  • 💴 No salary range given
  • 🏡
    Partially remote
  • 🗾 Japan residents only
  • 💬
    No Japanese required
    Business English
  • 🧪
    Intermediate level
    3+ years experience required
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

About the position

We’re hiring our second frontend engineer to work with our small, full-stack team to build products to evaluate, monitor, and govern AI systems. Our users rely on our product interfaces to visualize and understand complex details about their AI models, datasets, and workflows.

You’ll be responsible for designing and implementing product interfaces in our existing and new products, covering:

  • Evaluation: Quantitative testing of AI models and datasets
  • Firewall: Real-time monitoring of AI prompts and responses
  • Governance: System-of-record for enterprise AI use cases and workflows
  • As we scale our products, team, and business from the 1 → 10 stage, you will also contribute to modernizing our codebase and scaling our engineering processes.

You’ll primarily work with Svelte and shadcn/ui for new features, and vanilla JS, Bootstrap, and Jinja for existing features. Some technologies we use are: TanStack, Chart.js, Sveltekit, Vite, JSDoc, TypeScript, Vitest, Playwright.

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 3 years of frontend software engineering experience. We don’t require past experience with specific programming languages or frameworks, but knowledge of reactive frameworks such as React, Vue, or Svelte is desirable.

English is required and Japanese is preferred. 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 can work full-stack, you’ve worked at a startup before, or you have AI/ML/LLM experience.

Compensation

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

DO YOU NEED MORE INFO?
ASK A QUESTION

Related jobs

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.