OnlyShell is a reverse shell handler built with Go, designed for managing multiple shell connections at once. Its primary audience includes penetration testers and security researchers who need to handle various shell types efficiently. The tool can automatically detect different shell environments like bash and PowerShell, making it user-friendly for those with diverse targets. Users can start numerous listeners on different ports simultaneously, which is particularly useful in complex testing scenarios. The interface allows for real-time interaction with connected shells, plus features like command broadcasting to execute commands across multiple active shells at once. Background shell support means you can switch back and forth between tasks without losing connections. Additionally, OnlyShell provides a silent keepalive feature to monitor connections without interrupting ongoing sessions. Users can view the status of each shell—active, stale, or dead—along with timestamps for when they were last seen. To set up OnlyShell, the minimum requirement is Go 1.16. The installation process involves cloning the repository and building binaries for the desired platform. The tool supports cross-compiling, allowing users to create executables for Linux, Windows, and macOS. Commands for starting listeners, interacting with shells, and cleaning up dead connections are straightforward, making it accessible even for those newer to penetration testing. Security practices are emphasized throughout the documentation. Users are reminded to operate OnlyShell only on authorized networks and systems, to employ TLS for sensitive operations, and to be mindful of potential detection by logging mechanisms. The tool is open for contributions and feedback, and the project is licensed under the MIT License, ensuring flexibility for those who want to build upon it.