Is LanguageTool better than Harper?

LanguageTool ranks higher in our list of grammar and proofreading tools (#2 against #3, score 91.0 against 89.5), but the gap is small and the better choice depends on what you need. Harper is best for: private, free grammar checks on your own device. LanguageTool is best for: open-source checking in many languages.

Which is cheaper, Harper or LanguageTool?

Harper: Free and open source under Apache-2.0; no paid tier listed. LanguageTool: Free grammar checking; Premium adds unlimited paraphrasing and more features.

Do Harper and LanguageTool run on the same platforms?

Harper supports macOS, Browser extension. LanguageTool supports Web, Windows, macOS, Browser extension.

Comparison · Grammar and proofreading tools

Harper vs LanguageTool: which is better in 2026?

Harper89.5#3 in best grammar and proofreading tools

LanguageTool91.0#2 in best grammar and proofreading tools

LanguageTool ranks higher in our list of grammar and proofreading tools (#2 against #3, score 91.0 against 89.5), but the gap is small and the better choice depends on what you need.

How we rank Share

89.5
Editorial score
91.0
2
Platforms
4
Yes
Free to use
Yes
Yes
Open source
Yes

Which should you choose?

Choose Harper if you want

Private, free grammar checks on your own device.

Free, Apache-2.0 open source, with checks that run on your device. It covers grammar and spelling only, and its desktop app is listed for macOS.

Choose LanguageTool if you want

Open-source checking in many languages.

Open-source core under LGPL-2.1, with browser add-ons, Office plugins and many languages. Free checking is solid, but paraphrasing is limited on the free tier.

The main differences

Only LanguageTool runs on Windows.
Only LanguageTool runs on Web.
Harper is free and open source; LanguageTool is free plan, paid upgrades.

Side by side

	Harper	LanguageTool
Score	89.5	91.0
Rank in list	#3 of 10	#2 of 10
Price	Free and open sourceFree and open source under Apache-2.0; no paid tier listed	Free plan, paid upgradesFree grammar checking; Premium adds unlimited paraphrasing and more features
Free to use	Yes	Yes
Open source	Yes	Yes
Platforms	macOSBrowser extensionmacOS, Browser extension	WebWindowsmacOSBrowser extensionWeb, Windows, macOS, Browser extension
Made by	Not stated	Not stated
Where checks run	On your device, in browsers and editors	Browser add-ons, desktop apps and Office plugins
Rewrites and paraphrasing	None; no AI model in the loop	Paraphrasing, limited on the free plan
Style guidance	Grammar and spelling only	Style checking in many languages
Best for	Private, free grammar checks on your own device	Open-source checking in many languages
Strengths	Free and open source under Apache-2.0 Checks run on your device, with no telemetry Fast enough for live checks as you type	Core source code on GitHub under LGPL 2.1 Browser add-ons and Office plugins Covers dozens of languages
Limits	Desktop app is listed for macOS only No AI rewriting or tone suggestions	Paraphrasing is limited in the free version Less focused on generating new text than AI-first tools
Links	Visit site	Visit site

Questions about Harper vs LanguageTool

Is LanguageTool better than Harper?: LanguageTool ranks higher in our list of grammar and proofreading tools (#2 against #3, score 91.0 against 89.5), but the gap is small and the better choice depends on what you need. Harper is best for: private, free grammar checks on your own device. LanguageTool is best for: open-source checking in many languages.
Which is cheaper, Harper or LanguageTool?: Harper: Free and open source under Apache-2.0; no paid tier listed. LanguageTool: Free grammar checking; Premium adds unlimited paraphrasing and more features.
Do Harper and LanguageTool run on the same platforms?: Harper supports macOS, Browser extension. LanguageTool supports Web, Windows, macOS, Browser extension.