Private Grammar Checker - Harper icon

Private Grammar Checker - Harper

by Elijah Potter · writewithharper.com · Communication
FeaturedEstablished publisherManifest V3 Free
View in Chrome Web Store Data as of 15 Oct 2026

The private grammar checker for 21st Century English

Users
60K
+10K in 30 days
Rating
4.2 / 5
+0.03 in 30 days
Ratings
128
+9 in 30 days
Store rank
#3,093
#2,710 among extensions
Version
2.12.0
updated 2 Oct 2026

Users

monthly, 18 months
030K60KMay 2025Feb 2026Oct 2026
Latest, 15 Oct 2026: 60,000 usersMove the mouse over the chart for any month

Ratings count

monthly, 18 months
064128May 2025Feb 2026Oct 2026
Latest, 15 Oct 2026: 128 ratingsMove the mouse over the chart for any month

The Chrome Web Store rounds user counts down to the leading digit, so the user line moves in steps. The ratings count is exact and is the better signal of real adoption.

About Private Grammar Checker - Harper

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.

Growth

WindowUsersChangeRatingsRating
7 days0+0.0%0+0.04
30 days+10K+20.0%+9+0.03
6 months+30K+100.0%+47+0.13
1 year+53K+757.1%+113−0.33

Chrome Web Store search rankings

Where Private Grammar Checker - Harper appears when people search the store, with the 30 day change
Search phrasePosition30 days
grammar checker#16+1
grammar#17new

Version history

65 versions recorded
2.12.02 Oct 2026
2.11.017 Sep 2026
2.10.09 Sep 2026
2.8.013 Aug 2026
2.7.028 Jul 2026
2.6.024 Jun 2026
2.5.015 Jun 2026
2.4.05 Jun 2026

Details

Category
Communication
First seen
30 Apr 2025
Size
8.0 MB
Languages
en
Pricing
Free
Extension ID
lodbfhdipoipcjmlebjbgmmgekckhpfb

Permissions and risk

Moderate riskimpact 3, likelihood 1
Permissions
storagetabs
Site access
https://writewithharper.com/*

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