This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Software Engineer - Javascript based in the United States. This role offers the opportunity to build high-performance JavaScript solutions that power large-scale digital monetization systems. You will work on complex engineering challenges within the programmatic advertising ecosystem, helping optimize revenue opportunities for major publishers. As a senior technical contributor, you will influence architecture decisions, improve platform reliability, and deliver production-level code at scale. The position requires deep expertise in client-side development, auction technologies, and modern ad infrastructure. You will collaborate with experienced engineers while operating with a high degree of autonomy and ownership. This is an ideal opportunity for a problem solver passionate about JavaScript, TypeScript, performance optimization, and innovative technology solutions.