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Harper vs Trinka: catalog facts
Harper	Trinka
Free Free and open source.	Freemium Free to start, with paid plans including a Confidential Data Plan.
macOS, Web, Browser extension, Command line	Web
All checks run locally with no telemetry Works in browsers, editors and system-wide on macOS	Tuned for academic and technical writing Includes plagiarism, AI detection and citation tools
English only Rule-based checks do not rewrite text the way AI assistants do	Less suited to casual or marketing writing Strongest privacy guarantees are on a paid plan
Downloadable app, Web application, Browser extension	Web application
Open source	Closed source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is needed
Works offline	Needs internet
Official website Full listing and sources Checked September 26, 2026	Official website Full listing and sources Checked September 26, 2026

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