LanguageTool separates its checker from its AI training

The writer's problem

A writer choosing a grammar checker built partly on open-source tooling, rather than a fully commercial product, wants two separate questions answered from two separate documents: what the paid tier adds beyond the free checker, and what the company's privacy policy actually commits to about submitted text.

What the documents show

As retrieved on 16 September 2026, LanguageTool's Premium page states that Premium raises the per-text character limit to 150,000, adds more than 20,000 additional checks across a named set of languages including English, German, French, Spanish, Dutch, Polish and Portuguese, adds unlimited AI-powered sentence paraphrasing, and adds a personal style guide alongside browser add-ons across devices, offered at monthly, quarterly, annual or two-year intervals with a stated limited-time discount and a 14-day money-back guarantee. A separate Teams tier adds user management and a shared team dictionary and style guide. Separately, LanguageTool's privacy policy, published by parent company Learneo, states that data is retained for as long as an account stays open and for a commercially reasonable period beyond that, and states directly that Learneo does not use inputs from any LanguageTool user, on either an Individual or Team plan, to train its language algorithms or models, applying automatically without requiring an opt-out.

The editorial choice

The training-data commitment is stated identically for Individual and Team accounts in the policy, which is worth naming explicitly, since it means the no-training commitment is not something purchased along with Premium the way the 150,000-character limit or the paraphrasing tool is. An editorial reading of the two documents together suggests a cost-conscious writer can treat the training exclusion as already covering both the free and paid tiers, and make the actual upgrade decision purely on the checking-capacity features Premium adds, rather than on any privacy trade the free tier might otherwise seem to carry.

What stays with the author

The policy's retention language, a commercially reasonable period, is a general standard rather than a specific number of days describing how long a submitted excerpt sits on the company's servers before deletion, so a writer concerned about the confidentiality of an unpublished excerpt does not get a precise retention window from this document. What the policy does settle, more narrowly, is that the company's stated practice is not to use that excerpt to train its checking or paraphrasing models regardless of which tier submitted it, which is a real limit but not the same as a guarantee about how long the raw text itself persists.

• Does the free tier's lower character limit actually constrain the length of text being checked at once?
• Is the specific retention period for submitted text, beyond the account's open status, acceptable for the material involved?
• Do the languages covered by the additional 20,000 checks include the one the manuscript is written in?

LanguageTool's two documents draw a clear line between what Premium sells and what its privacy policy promises, and the useful reading is that the second does not depend on paying for the first.