open source★ 14kactive aug 2026
Harper
A fast English grammar checker that stays on your device and mostly keeps its opinions to itself.
Technical Profile & Specs
- Cost
- $0 / forever (Open Source)
- Platforms
- desktopmobileextensionone-click install
Replaces 2 paid apps
up to $35.47/mo ($426/yr) in subscriptions
Harper FAQ
Common questions
Is Harper free and open source?+
Harper is an open-source tool. A fast English grammar checker that stays on your device and mostly keeps its opinions to itself.
What paid software does Harper replace?+
Harper serves as a free replacement for 2 paid SaaS applications: Grammarly, LanguageTool, saving up to $35.47/month ($426/year) in subscription bills.