Mass Assigner is a tool that identifies mass assignment vulnerabilities in web applications by retrieving data from a specified request and applying extracted parameters to a second request. It supports customization of HTTP methods, addition of custom headers, and rate-limiting. Mass Assigner ignores specified parameters during execution and supports nested arrays/objects in JSON data. Installation involves installing requirements using pip3. Arguments include --fetch-from, --target-req, --header, --proxy, --data, --rate-limit, --source-method, --target-method, and --ignore-params. Example usage demonstrates how to set parameters and specify custom headers, proxy, and data. Mass Assigner actively modifies server-side data, so authorization is required before use. Unauthorized or illegal activities are at the user's own risk. Future plans include support for additional content types. Download Mass Assigner to enhance your web application security testing.