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

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