Memex
Save, annotate, and resurface everything you read online with AI-powered search
About Memex
Memex (by WorldBrain) is a privacy-first browser extension and web research assistant that lets you bookmark, highlight, annotate, and organize everything you read online. Named after Vannevar Bush's visionary concept of an extended memory machine, Memex aims to make your entire web browsing history a searchable, reusable knowledge base. The tool works across Chrome, Firefox, and mobile (iOS/Android), and stores all data locally by default so your reading history never leaves your device. You can annotate websites, PDFs, and YouTube videos, organize content into collections, and use full-text search to find anything you've ever saved. AI-powered features let you summarize pages and chat with your saved content, while an MCP server integration means you can connect your knowledge base directly to LLMs like Claude and GPT. Memex is open-source and operated under a Steward Ownership model — meaning the company cannot be sold to investors. It targets researchers, writers, and knowledge workers who need a durable, private alternative to cloud-dependent bookmarking and note-taking tools.
Pros & Cons
Pros
- Privacy-first — all data stored locally by default
- Open-source and independently owned under Steward Ownership model
- Works across web pages, PDFs, and YouTube content
- MCP integration enables direct use with Claude, GPT, and other LLMs
- Generous free tier for basic bookmarking and annotation
Cons
- Browser extension adds friction compared to native desktop apps
- Heavy AI usage requires a paid plan
- Small independent team means slower feature pace than VC-backed competitors
- Cross-device sync requires a paid plan
Key Features
Browser Extension
Works in Chrome and Firefox to capture and annotate any webpage as you browse
Highlight and Annotate
Add highlights and notes directly on webpages, PDFs, and YouTube videos without leaving the page
Full-Text Search
Search across the full text of every page, PDF, and annotation you have ever saved
Collections and Tags
Organize saved content into named collections and apply tags for flexible retrieval
AI Summarization and Chat
Summarize any saved page or PDF and ask questions about your saved knowledge base using AI
MCP Server Integration
Connect your Memex knowledge base directly to LLMs like Claude and GPT via the Model Context Protocol
Local-First Storage
All data stored on your device by default — no cloud upload required for privacy
Mobile Apps
iOS and Android apps let you save and annotate content on the go
Open Source
Fully open-source codebase available on GitHub for transparency and community contributions
Collaboration
Share annotated pages and collections with teammates or the public
Pricing
- Browser extension (Chrome and Firefox)
- Bookmarking and annotations
- Collections and tags
- Limited AI credits per month
- Local data storage
- Everything in Free
- Unlimited AI credits
- PDF annotation
- YouTube video annotation
- MCP server integration
- Mobile apps (iOS and Android)
- Priority support