Simple Modify Headers is a Firefox extension tailored for web developers and IT professionals who need to manipulate HTTP(S) headers effectively. This subscription-based tool enables users to add, modify, or delete header fields for both requests and responses, streamlining header configuration management. The extension supports exporting configurations in JSON format, allowing for easy integration with the Modifyheaders plugin, which enhances its utility for users familiar with header manipulation.

Additionally, Simple Modify Headers allows users to specify the URLs to which the modifications will apply, offering precise control over web development tasks. Its open-source code, available under the Mozilla Public License 2.0, underscores its commitment to transparency and customization, making it an essential resource for developers focused on testing and optimizing header settings.