A Capistrano developer is responsible for automating the process of deploying web applications. They use Capistrano, a remote server automation tool written in Ruby, to deploy applications reliably and efficiently. They script and automate tasks that are performed on remote servers, reducing the likelihood of errors and streamlining the process. They also manage and maintain multiple stages of deployment, such as testing, staging, and production. Additionally, they troubleshoot issues that arise during deployment, backing up and restoring applications as needed. Their work is crucial in ensuring seamless transitions between different stages of application development and deployment.