Bloom is a YC backed startup building the future of app development. Backed by leading U.S. investors, we are establishing our Swiss subsidiary in Zürich, to grow our engineering team.

We are seeking a Founding Convex Engineer who will lay the foundation of our technical infrastructure and, depending on fit, grow into our CTO role. This role requires a rare combination of advanced Convex, Expo, and React expertise, with demonstrable experience in building and scaling full-stack applications in production.

Core requirements:

1. Convex expertise:

• Minimum 2 years hands-on experience with Convex in production.
• Deep knowledge of advanced Convex modules: Real-time query subscriptions, row-level security and access control enforcement, schema evolution and database migrations, query optimization and indexing strategies.
• Proven ability to design and maintain complex Convex schemas at scale.

2. Expo expertise:

• Minimum 2 years building and shipping production apps with Expo.

Experience with:

• Expo Application Services (EAS) builds.
• Over-the-air (OTA) updates.
• Deep linking and navigation.
• Push notification pipelines.
• At least one published app in the App Store or Google Play built with Expo.

3. React/TypeScript expertise:

• Demonstrated mastery of React concurrent features (Suspense, concurrent rendering).
• Advanced state management experience (React Query, Recoil, or equivalent).
• Deep knowledge of TypeScript type-safety in large-scale applications.
• Contributions to open-source React/TypeScript projects (with GitHub proof).

4. AI integration skills:

• Practical experience with LLM-driven developer tools, including coding agents, retrieval-augmented generation (RAG), fine-tuning, and evals.
• Ability to design developer workflows where AI generates schemas, APIs, or UI components automatically.

5. Portfolio proof:

• GitHub profile with at least two large-scale projects demonstrating Convex + Expo integration.
• Evidence of production deployments (live apps, OSS contributions, or technical talks/blogs).

6. Startup mindset:

• Prior experience at a YC startup or as a founder.
• Demonstrated ability to operate with high agency in fast-paced environments.
• High levels of endurance.

Bonus Points

• Strong background in Swift/Kotlin/React Native.
• Experience architecting multi-tenant mobile app backends.
• Contributions to Convex or Expo open-source communities.
• Proven record of mentoring engineers or leading small teams.
• Graduate of top 10 engineering schools worldwide.
• Hackathon winner.

What You'll Work On

• Designing core Convex schemas and APIs to power an AI agent capable of generating production-grade mobile apps.
• Solving difficult technical challenges including schema migrations, authentication/authorization, payments, and real-time reliability across thousands of subscriptions.
• Building an Expo client that demonstrates seamless integration with Convex and showcases AI-assisted app creation.
• Developing tools that give creators insight, control, and scalability for their apps.
• Establishing the long-term technical architecture and engineering culture of Bloom.

Benefits

• Fast growth curve
• Top quartile compensation
• Options
• Beautiful office 1 min from ETH Zürich
• Best in-class Apple hardware

How to Apply

• Provide GitHub links proving Convex, Expo, and React expertise.
• Share evidence of published Expo apps in App Store/Google Play.
• Describe your experience with AI-powered developer tools.
• Include your thoughts on solving Bloom’s open problems.

Interview Process

• Vibe check with COO
• Advanced Convex take-home task
• Call with both Co-Founders