If you're looking for a replacement for Readwise, Glasp is a good candidate. Glasp is a web-based and PDF highlighting and note-taking tool that lets you collect, curate and share your favorite quotes and ideas from the web. It's notable for its ability to highlight and annotate websites and PDFs, categorize and tag highlights, export to popular note-taking apps, and import and review Kindle highlights. Glasp offers a free plan with unlimited public highlights and export, and a Pro plan for $10/month that includes private highlights and daily auto-sync/export to Notion.
Another contender is Reflect. Reflect is a note-taking app that uses AI for features like voice note transcription, article summarization and grammar checking. You can link notes with backlinks for quick information retrieval and can import web clips and Kindle highlights across devices. Reflect supports networked note-taking, web clipping and Kindle offline sync, and integrates with services like Zapier, Google and Outlook. It costs $10 per month, billed annually, so it's a powerful option for capturing and getting use out of your digital highlights.
If you're looking for something more of a learning and retention system, Recall is worth a look. Recall uses AI to summarize and archive online information like blog posts, PDFs and articles, and it connects new information to what you already know. The service has features like spaced repetition to help you learn and export data in Markdown format. Recall works offline and protects your data, available as browser extensions and mobile apps, with a free version and a Plus Plan for $7 per month (billed annually).