- Calibre Plugins: Enhance your Calibre app with a variety of plugins available at GitHub - Calibre Plugins by a great developer, or explore the complete directory.
- K2pdfopt: Converts PDF to a format readable on Kindle. More information can be found on MobileRead Forums.
- Page Count and Readability Indexes: Adds a page count column and readability indexes to the Calibre app. Details are available on GitHub - Count Pages Wiki.
- Emdash: An AI-powered wisdom indexer that organizes text snippets for better recall and learning, functioning completely offline. Open-source and free. GitHub - Emdash.
- Remind Kindle: Sends reminder emails from your Kindle highlights using Clippings.txt or web highlights. GitHub - Remind Kindle. Note: Glasp.co offers a similar service.
- Librarian: Offers a website to manage your clippings library. It's unclear whether it allows for storage or search of highlights. GitHub - Librarian.
- KindleClipping: A Japanese app for managing Kindle clippings. GitHub - KindleClipping.
- Clippings.io: A paid service ($2/month) that provides professional management of Kindle highlights and sends them via email. Clippings.io Website.
- Glasp: A professional service for managing highlights that integrates with Kindle. It sends daily emails with your Kindle highlights. Glasp Website.
- PDF Planner with Clickable Links: https://github.com/kudrykv/latex-yearly-planner
- Dear Reader: https://github.com/javierarce/dear-reader