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Dia vs HARPA AI: catalog facts
Dia	HARPA AI
Freemium A free tier is available. Heavier use requires a paid plan.	Freemium Free to install, with paid plans for heavier use of hosted models.
macOS	Browser extension
Assistant reads your open tabs, so questions do not need copy and paste	Works with many AI providers and local models YouTube, PDF and page summaries in place
macOS only and requires an account The assistant sends page content to a remote service, which has privacy implications	Mainly a Chrome extension Hosted models send page content to third-party AI providers
Downloadable app	Browser extension
Closed source	Closed source
License not stated	License not stated
Account needed	Not stated if an account is needed
Not stated if it works offline	Needs internet
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 23, 2026

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