Founding Engineer [Rainbow Fintech]

About Us

The pain is universal: finance teams stitch together spreadsheets and dashboards just to answer basic questions about their cash flow. They feel constantly behind — reactive instead of in control. By the time their systems tell them what happened, it’s too late to optimize.

This directly hits the bottom line — costing companies millions in lost yield and avoidable borrowing. But it’s also a once-in-a-generation opportunity for AI-native contenders.

Rainbow is building an AI-powered treasury system of action for global companies — turning forecasts into execution with the intelligence and reliability modern finance demands. We’re backed by Bessemer Venture Partners, Vertex Ventures, Hanaco Ventures, and leading angels in fintech, and work with companies ranging from private mid-market to public enterprises.

The Inevitable Future: Every company becomes financially intelligent. We’re building the foundation for that future now.

The Role

Join Rainbow as a Founding Engineer working across customers and product. You’ll go deep into real treasury workflows, solve them hands-on, and translate those learnings into scalable product and architecture with the core engineering team.

We’re looking for a product-minded builder — someone who likes to get close to the problem, craft working software end-to-end, and turn complexity into elegant systems. You’ll iterate fast, build with users, and help shape the product and engineering culture from day one.

• What You’ll DoDesign and build AI-powered treasury automation systems from scratch
• Work directly with enterprise customers to understand workflows and implement solutions
• Develop APIs, data pipelines, and automation services that handle critical financial operations
• Lead technical decisions across the stack (backend, data, AI/ML, cloud)
• Own complex projects from concept to production, with autonomy and accountability
• Contribute to product UX and be comfortable jumping into frontend when needed
• We’re Looking For Someone WhoHas a strong track record of end-to-end product development and a builder mindset
• Is experienced with modern backend development — Python/TypeScript/Java/Golang
• Is comfortable contributing to the frontend when needed (React/TypeScript a plus)
• Is familiar with cloud-native development, APIs, and modern infrastructure
• Has experience with AI/ML systems, LLMs, or automation workflows
• Thrives in customer-facing environments and enjoys turning needs into product
• Takes ownership, moves fast, and can navigate complexity and ambiguity

Bonus: Experience building AI agents in production, or financial/enterprise software.

This isn’t a role for someone who only wants to sit behind a keyboard. It’s for someone who wants to live in the problem space, work with customers, and use those insights to build a category-defining product.