Senior AI Software Developer (Fintech)

About Us

Rainbow is on a mission to reinvent treasury. Today, companies still rely on spreadsheets and manual workflows to manage billions in cash flows. We’re building the first AI Treasurer — a modern platform that automates liquidity, funding, and investment decisions so finance teams can focus on strategy. We’re backed by top investors like Bessemer, Vertex, Hanaco, and leading angels, and already helping companies manage billions with measurable ROI.

The Role

We’re looking for a Senior AI Software Developer to join Rainbow as a founding team engineer. This is a unique opportunity to shape our technical foundation, architecture, and engineering culture from the ground up. You’ll collaborate directly with customers, design intelligent automations, and build production-ready systems that replace manual processes with scalable AI-driven execution.

From backend services to frontend features, you’ll work across the stack to bring the AI Treasurer to life — creating the infrastructure that moves money smarter and faster than ever before.

What You’ll Do

* Shape Rainbow’s AI-first product and technical direction as a founding engineer.
* Engage with customers to understand workflows and design AI automations and agents.
* Build end-to-end AI-powered systems: data pipelines, models, and production deployment.
* Develop and maintain TypeScript/NestJS backend services powering scalable AI features.
* Contribute to React frontend code for seamless product experiences.
* Apply DevOps skills to deploy, monitor, and maintain cloud-based AI systems.
* Ensure strong architecture, observability, and CI/CD pipelines.
* Work closely with leadership and product to influence the roadmap with technical insights.
* Contribute to company-wide engineering practices and mentor future hires.

About You

* 5+ years of professional software development experience.
* Strong skills in backend languages (Python, TypeScript, Java, or Go).
* Solid understanding of distributed systems and modern architectures.
* Proven experience deploying production systems with CI/CD and observability.
* Familiarity with AI developer tools (Cursor, Copilot, Claude Code, or similar).
* Excellent communicator who enjoys engaging with customers.
* Comfortable in startup environments — adaptable and execution-focused.

Nice to have:

* Experience in fintech or enterprise software.
* Experience building AI agents.
* Prior role as a founding engineer or early-stage contributor.

What We Offer

* The chance to be part of the founding team in a high-growth, AI-first startup.
* Direct ownership of core technical decisions and product direction.
* Close collaboration with customers and industry experts.
* Competitive compensation with meaningful equity.
* A culture built on innovation, speed, and impact.

Job Type: Full-time