Sigil

igil is a free, open-source, cross-platform EPUB eBook editor designed for authors, editors, and publishers who require precise control over the formatting and structure of their digital publications. Compatible with Windows, macOS, and Linux, Sigil offers a comprehensive suite of tools tailored for editing and creating eBooks in the EPUB format.

The application supports both EPUB 2 and EPUB 3 standards, providing users with multiple editing views, including Code View and Preview View. This flexibility allows for direct manipulation of the underlying XHTML and CSS, ensuring that users can fine-tune every aspect of their eBook's presentation. Features such as a multi-level Table of Contents generator, metadata editor, and integrated spell checker enhance the editing experience. Additionally, Sigil supports regular expressions for advanced find-and-replace operations, and its plugin architecture allows for extended functionality, including EPUB validation tools.

Originally developed in 2009 by Strahinja Val Marković, Sigil has evolved under the stewardship of developers Kevin Hendricks and Doug Massay. Its commitment to open-source principles and a user-centric design makes Sigil a preferred choice for professionals seeking a robust and customizable EPUB editing solution.