Compare software

Harper vs proselint: catalog facts
Harper	proselint
Free Free and open source.	Free Free and open source under the BSD 3-Clause licence.
macOS, Web, Browser extension, Command line	Windows, macOS, Linux, Command line
All checks run locally with no telemetry Works in browsers, editors and system-wide on macOS	Checks based on established usage guides and editors Works on plain files from the command line
English only Rule-based checks do not rewrite text the way AI assistants do	English only No graphical interface
Downloadable app, Web application, Browser extension	Downloadable app
Open source	Open source
License not stated	License: BSD-3-Clause
Not stated if an account is needed	No account needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked September 26, 2026	Official website Full listing and sources Checked October 2, 2026

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