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OpenDisplay vs Duet Display: catalog facts
OpenDisplay	Duet Display
Free Free and open source under GPL-3.0, with optional donations.	Paid Paid app with plans listed on the pricing page.
macOS, iOS	Windows, macOS, Android, iOS
True extended display, not just mirroring Works over USB or Wi-Fi with touch and scroll input	Uses tablets and phones as extra monitors Drawing tablet mode for illustration
Only extends Macs; Windows and Linux hosts are not supported Maintained by a single developer	Paid, with features split across plans Requires an account
Downloadable app	Downloadable app
Open source	Closed source
License: GPL-3.0	License not stated
No account needed	Account needed
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 October 1, 2026

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