Private Grammar Checker - Harper

The private grammar checker for 21st Century English

Users30K

Rating4.1

Reviews87

Manifest versionV3

7-day growth+10K

7-day growth rate+50%

Preview

Private Grammar Checker - Harper Media preview

3 assets

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30-day user trend

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User Growth Over Time

Rating trend

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30-day rating change

Start

4.11

Latest

4.09

30-day rating change

-0.02

2026年5月29日2026年6月4日

Growth overview

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1-day growthFlat

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7-day growthGrowing

+10K+50%

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Technical snapshot

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Version1.12.0

ManifestV3

Size15.46MiB

Languages1English

Published--

Store updated--

Last crawled--

Overview

Product summary

Review the store description, core capabilities, and common use cases.

Harper is an English grammar checker designed to be just right. I created it after years of dealing with the shortcomings of the competition.

Grammarly was too expensive and too overbearing. Its suggestions lacked context, and were often just plain wrong. Not to mention: it's a privacy nightmare. Everything you write with Grammarly is sent to their servers. Their privacy policy claims they don't sell the data, but that doesn't mean they don't use it to train large language models and god knows what else. Not only that, but the round-trip-time of the network request makes revising your work all the more tedious.

LanguageTool is great, if you have gigabytes of RAM to spare and are willing to download the ~16GB n-gram dataset. Besides the memory requirements, I found LanguageTool too slow: it would take several seconds to lint even a moderate-size document.

That's why I created Harper: it is the grammar checker that fits my needs. Not only does it take milliseconds to lint a document, take less than 1/50th of LanguageTool's memory footprint, but it is also completely private. That's the power of open source.

Reviews