Overview
The private grammar checker for 21st Century English
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.
Details
- Version2.13.0
- UpdatedOctober 16, 2026
- Size8.06MiB
- LanguagesEnglish
- DeveloperElijah PotterWebsite
16500 South Golden Road 428 Golden, CO 80401 USEmail
me@elijahpotter.devPhone
+1 720-643-3720 - TraderThis developer has identified itself as a trader per the definition from the European Union and committed to only offer products or services that comply with EU laws.
Privacy
This developer declares that your data is
- Not being sold to third parties, outside of the approved use cases
- Not being used or transferred for purposes that are unrelated to the item's core functionality
- Not being used or transferred to determine creditworthiness or for lending purposes