AI grammar editing: LanguageTool vs Grammarly vs ProWritingAid

Improving a draft you have already written

Grammar editing starts with words the writer already wants to say. LanguageTool, Grammarly and ProWritingAid help revise that draft, but differ in language coverage, how they present feedback and the depth of analysis. This comparison focuses on correction and style editing, rather than asking a general assistant to generate a new article from a prompt.

LanguageTool

LanguageTool checks spelling, punctuation, grammar and style across more than 30 languages and dialects. Its main supported languages include English, German, Spanish, French, Dutch and Portuguese, with the depth of advanced checks varying by language. The product combines ordinary corrections with an AI sentence rephraser that can make supported text more formal, more fluent or shorter. This makes it relevant to a writer who alternates between several languages and wants an editing layer rather than a blank-page generation tool.

Browser add-ons, desktop applications and office integrations put those suggestions alongside existing work. The free web checker handles basic errors, while Premium adds enhanced checks and unlimited sentence paraphrasing. Integration availability should not be read as a promise that every extension feature is free. During this review, the Premium page displayed monthly, annual and two-year choices but explicitly failed to display the numeric prices. LanguageTool therefore has a documented plan structure without a verified current amount in the profile. Its money-back guarantee is also distinct from a permanent free service.

Grammarly

Grammarly centers on suggestions that appear where people write, including supported desktop applications, browser fields and document tools. The free plan covers spelling, grammar and tone-related feedback; Pro adds clearer sentence revisions and personalized suggestions. Paragraph rewrites let a user revise a selected passage instead of opening a separate drafting conversation. That suits someone editing emails, workplace documents and other everyday text in the applications they already use.

Grammarly should no longer be described as English-only. Its official multilingual announcement includes grammar and spelling corrections in Spanish, French, Portuguese, German and Italian, while current support describes paragraph rewriting in those languages plus Ukrainian. The features and supported application surfaces are not identical across languages. Sales-managed licenses may also require an administrator to enable paragraph rewrites. Pro pricing is per member and distinguishes monthly, quarterly and annual charges. The plan grid’s monthly generative prompt allowance is separate from the ordinary correction workflow, so it is not a count of how many spelling errors can be fixed.

ProWritingAid

ProWritingAid combines grammar, spelling and punctuation with a more detailed view of an English manuscript. Its writing reports examine readability, repetition, consistency, style and other patterns, and users can choose document types and English variants. A writer can investigate why a passage feels repetitive or why usage changes halfway through a chapter, rather than only accept individual underlines. This is particularly useful for authors and long-form writers who want feedback on an existing body of work.

Its paid packages also include customizable suggestions, a style guide and unlimited line-editing report runs. Sentence rephrasing is available, while story critiques and whole-manuscript tools extend into a separate layer of analysis. The current Free tier is specific: two runs per line-editing report each day on 500 words and ten daily Rephrases. Premium removes the line-report run limit, but advanced story analysis can still consume separate Story Credits. That distinction matters when comparing the editing subscription with broader storytelling products; a lifetime license does not automatically mean unlimited use of every credit-based analysis tool.

Language coverage and the kind of feedback

LanguageTool is the broadest explicitly multilingual checker in this shortlist, with more than 30 languages and dialects and a narrower set of supported AI rephrasing languages. Grammarly now covers several non-English correction workflows, so the choice should depend on the precise language and feature rather than an outdated English-only assumption. ProWritingAid focuses this comparison on English variants and detailed manuscript reports. For multilingual daily correspondence, LanguageTool’s coverage is a useful starting point. For English fiction or long-form nonfiction, ProWritingAid’s repetition and consistency reports answer questions that a quick grammatical correction alone does not.

Editing in place or analyzing the manuscript

Grammarly’s strength is its in-context correction and revision across supported writing surfaces. LanguageTool offers a similar integration-led route with an emphasis on multilingual checking and sentence alternatives. ProWritingAid is particularly explicit about deeper reports, document types and author-oriented customization, although it also provides integrations. Someone finishing a short email may value a quick clarity suggestion more than a detailed report. Someone revising a chapter may prefer to examine recurring patterns across the passage. These workflow choices do not require assuming that more automated rewrites always produce a better voice; the writer can accept only changes that preserve the intended meaning.

What the paid plans actually add

LanguageTool Premium adds advanced checking and unlimited sentence paraphrasing, but its current public price-display error prevents a reliable numerical quote. Grammarly Pro combines full-sentence revisions and personalized suggestions with a separately metered generative allowance; the annual monthly equivalent is paid as a yearly charge. ProWritingAid Premium adds unlimited line-report runs and Rephrases, with monthly, yearly and one-time license choices, while Story Credits remain separate. ProWritingAid’s Free limits are expressed in words and report runs, rather than a general promise of unrestricted manuscript editing. Comparing those units is more useful than treating every plan’s word unlimited as referring to the same operation.

Which editing assistant fits your writing?

Choose LanguageTool for broad multilingual correction, Grammarly for everyday clarity and rewriting in supported apps, or ProWritingAid for detailed English manuscript analysis. Start with the feedback you need, then check the language, integration and plan entitlement that delivers it. None of these products replaces the writer’s judgment about meaning and voice.