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Nook vs SigmaOS: catalog facts
Nook	SigmaOS
Free Free and open source, supported through Open Collective.	Freemium A free tier is available. Heavier use moves to a paid subscription.
macOS	macOS
Sidebar and spaces for organising tabs Runs both Chrome and Safari extensions	Tabs live in named workspaces with separate logins, and each one can be marked done or locked, which…
macOS only Young project, recently reached version 1.0	It is closed source, macOS-only, and the free tier is limited enough that regular use pushes you to…
Downloadable app	Downloadable app
Open source	Closed source
License not stated	License not stated
No account needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked September 22, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.