This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Product Engineer, Treasury (Elixir) based in the United States. Join an innovative engineering team building an AI-powered finance platform that transforms how enterprises manage payments, treasury, and financial operations. As a Senior Product Engineer, you will design and scale the core services behind a treasury platform handling billions in transaction volume. Your work will help enable next-generation financial workflows, including AI agents that initiate corporate expenses, manage travel, and use payment cards. Working closely with founders and a small, senior team across engineering, product, treasury, and data/AI, you will shape product direction and technical architecture. This hands-on role combines deep Elixir expertise with end-to-end product ownership, from defining requirements and building interfaces to operating reliable production systems. The position is fully remote for US-based candidates working Eastern Time hours, with significant autonomy and opportunities to influence the future of financial technology.