kOS
kOS simplifies research and provides proof of work with AI tools.
At a glance
Starts at
$9.99 per month
Price as published by the vendor, September 2026.
Free tier
Yes, limited
Platforms
macOS
Best for
Educators, researchers
Not for
Teams requiring real-time collaboration
4.0 out of 5
Scored by Alex after real useOur verdict
kOS simplifies the creation of annotated PDFs for research, but macOS-only limits its reach.
✓What it does well
Simplified Research ProcessEasily annotate and share research documents with citations.
AI IntegrationAsk the AI questions about any document, section or excerpt.
Private StorageNo Internet required for private, secure folder storage.
✕Where it falls short
MacOS-OnlyWorks only with macOS and PDFs; no web-based version yet.
Limited Free PlanFree tier limited to basic features without a subscription.
No Web-Based VersionWeb-based support not available, currently only for macOS and PDFs.
Key features
PDF SupportAdd, annotate, organize, and present multiple PDF files easily.
AI AccessConverse with the AI to generate summaries or ask questions about documents.
Private FoldersCreate private folders that don’t require internet access for secure storage.
Web IntegrationSupport for multiple file types and web content