# Harper

> Apache-2.0 offline privacy grammar checker — Rust (Automattic)

**Category:** Rust  
**Pricing:** open-source  
**URL:** https://writewithharper.com  
**GitHub:** https://github.com/Automattic/harper  
**Added:** 2026-09-15

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## The Hook

Harper is Automattic’s offline, privacy-first grammar checker — fast, open-source, Rust-powered, no document phone-home.

## What's Good

Apache-2.0 (Automattic/harper). Local grammar/style checking with editor/LSP/Obsidian integrations. Docs and product at writewithharper.com. Runs on your machine; aimed at writers who refuse to paste drafts into SaaS grammar boxes.

## The Catch

Vs Grammarly SaaS: Harper is offline Rust grammar, not a cloud writing coach with tone/generative rewrites and team admin. Rule coverage and language support differ from Grammarly’s product surface — try it on your real prose. Not an LLM writing agent.

## Verdict

Apache-2.0 offline grammar. Privacy-local vs Grammarly cloud.