Harper
Offline, privacy-first grammar checker.
None realistic. A personal tool.
Saves a subscription. Not a service.
Apache-2.0 (LICENSE file; site confirms Apache-2.0)
Yes - Apache-2.0, runs fully offline on the user's device, no restrictions found.
Active (pushed 2026-10-07). Owned by Automattic (footer '(c) 2026 Automattic Inc.'; creator Elijah Potter works there). English only. Rule-based, no LLM, no GPU, no API keys. It is a grammar checker, not an AI rewriting tool.
You
None realistic. A personal tool.
none found (site FAQ: 'Harper is free in every sense of the word'; no paid plans)
Grammarly (README and site: 'the private alternative to Grammarly'). Grammarly page today: Free $0; Pro $12 USD (billing period not shown on the page); Enterprise 'Contact Sales'.