This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Developer (Freelance) based in United States. The Senior Developer will join an established client engagement and help strengthen, maintain, and evolve an existing digital application. This freelance opportunity is focused on reducing technical debt and improving the overall health, accessibility, and maintainability of a production experience. You will work within an established team and sprint cadence, taking ownership of assigned technical work from investigation through completion. The role requires strong troubleshooting abilities and the confidence to identify and resolve issues independently with minimal oversight. You will collaborate closely with backend engineering, QA, and Production teams to manage dependencies and maintain consistent delivery. The ideal candidate brings senior-level frontend or full-stack development experience and can quickly become productive within an unfamiliar codebase. This is a focused short-term engagement offering the opportunity to make a meaningful technical impact within an active digital product environment.