Mercury is a comprehensive HTML5 editing tool designed to maximize your team's content editing experience in contemporary web browsers. Constructed from the ground up, it is packaged as a Rails Engine, allowing easy integration by simply adding it to your Gemfile, or you can choose to download the complete package if you're not utilizing Rails. The editor maintains the integrity of your production pages by not injecting any JavaScript or CSS, giving you the flexibility to implement any frameworks without concerns about conflicts. You can effortlessly customize the toolbar by adding or removing items, or even create entirely new tools to suit your needs. Each toolbar item can be linked to specific actions through behaviors and the command pattern, enhancing functionality. Mercury supports various content types out of the box, including Full HTML, Simple, Markdown, Snippet, and Image regions, while also allowing you to extend the foundational regions to create custom types. Built upon the advanced features of HTML5 contentEditable, it seamlessly supports all the modern HTML5 elements, syntax, and JavaScript APIs, making it a robust choice for developers looking to streamline their content editing process. The flexibility and extensibility of Mercury make it a valuable asset for teams aiming to improve their web content management capabilities.