Leanpub (http://leanpub.com) is an innovative platform that enables authors to publish and sell their books while they are still writing them. This unique approach allows for iterative, agile book creation, where authors can release chapters or updates as they go, receiving feedback from early readers to refine and improve the content. Leanpub provides a versatile medium not only for authors but also for software developers, and educators, offering tools to write both fiction and non-fiction, or to create and distribute course materials. In addition to providing a straightforward publishing and e-commerce solution, Leanpub boasts a robust community of readers and writers, fostering a collaborative environment that enhances the publishing process. It supports various output formats such as PDF, EPUB, and MOBI, ensuring the content is accessible on multiple devices.