aiCat vs LanguageTool
LanguageTool: generous free tier; Premium starts from about $5/month on an annual term. aiCat: free to start, Premium starts from $6/month. Neither is a superset of the other, and this page says which is which.
LanguageTool is the one comparison on this site where the competitor is cheaper, and it is worth saying that plainly. It is also the only one you can run on your own hardware today without a sales call. What it does not do is read for meaning — and the errors that embarrass you are almost never grammatical.
What follows is written to be usable by somebody who ends up choosing LanguageTool. Prices are floors — the cheapest tier each product is honestly available at — checked in August 2026 and worth re-checking on the vendor's own page before you decide on price alone.
Rules and models, compared
| aiCat | LanguageTool | |
|---|---|---|
| How it decides something is wrong | A model reads the sentence and judges it, including what it means | Linguistic rules plus some ML — deterministic and explainable |
| Languages | Whatever the model speaks | Thirty-plus, checked properly rather than as an afterthought |
| Self-hosting | Local models on the Team + Offline plan | Mature: an open-source server you can run yourself today |
| Beyond grammar | Translate, explain, fact-check, detect AI, dictate, read aloud | Grammar and style, with AI rewriting on top |
| Where it runs | Every application, at OS level, on three platforms | Browser extensions, Office and Docs add-ins, desktop apps |
| Repeatability | A model, so two runs can differ | Rules, so they do not |
| Facts | Claim-by-claim check with sources | Not attempted |
| Price floor | Free; Premium starts from $6/month | Free tier that does a lot; Premium starts from about $5/month |
What a model catches that a rule cannot
- Rewriting at the level of meaning, not only rule matching
- Translation, explanation, fact-checking, AI detection, dictation and read-aloud on the same keys
- Works in a terminal, a native IDE and a PDF viewer, where no extension reaches
- A memory that carries your projects and names between requests
What LanguageTool has that no model gives you
- A self-hosting story that is mature today, not a roadmap item
- Very hard to beat on price for pure grammar checking
- Thirty-plus languages checked by real linguistic rules rather than a model's judgement
- Deterministic: the same sentence gets the same correction twice
Which one your constraints point at
Text must not leave your network
LanguageTool, self-hosted. aiCat's local models need the Team + Offline plan; LanguageTool's server is free to run.
You want the cheapest credible grammar checker
LanguageTool. It starts from about $5 and the free tier is real.
The mistakes that hurt are factual, not grammatical
aiCat. A rule engine cannot tell you a claim is unsupported.
You need translation or dictation as well
aiCat. LanguageTool is a grammar checker and does not claim otherwise.
You want the same correction every time
LanguageTool. Determinism is a feature and models do not have it.
Hands-on: the same hundred sentences through both
One person's account of using both. It is an opinion, it is not a benchmark, and it is here because the rest of this page is a table.
A hundred sentences pulled out of a month of real Slack and email went through both. LanguageTool caught more raw typos, and caught them faster and without a network round trip on the self-hosted server. It missed every one of the eleven sentences that were grammatically flawless and wrong — a wrong figure, a claim that did not follow, a phrase that means something different to a native reader. aiCat caught nine of those eleven and invented one objection that was not real. If your errors are commas, the free tier of LanguageTool is genuinely the answer; if your errors are meaning, no rule engine is going to find them.
Stay on LanguageTool if privacy or price is the constraint
If the constraint is price, privacy or predictability, LanguageTool wins on all three. A self-hosted server means text that never leaves your network, which is a stronger guarantee than any policy document, and rules that produce the same correction twice are easier to trust than a model that does not.
aiCat is the better answer when the failure you are worried about is a sentence that is perfectly grammatical and wrong, or when the text is somewhere an extension cannot go.
Try aiCat on the text LanguageTool cannot reach
Free to start, 10 aiCatCoins included, no card. macOS, Windows and Linux.
aiCat pricing at a glance
| Plan | Price | aiCatCoins / month | Max selection | What it unlocks |
|---|---|---|---|---|
| Free | $0 | 10 | 500 chars | Everything aiCat does, plus free dictation and your own memory |
| Premium | from $6/mo (list $10) | 3 000 | 5 000 chars | Think More, read-aloud, encrypted memory, premium models |
| Team + Offline | from $18/member | 12 000 | 50 000 chars | Edit your memory, MCP access, local models, team sync |
| Enterprise | from $90/member | 150 000 | Unlimited | SSO, audit, best coin rate |
Read the whole page? Then you were deciding. Try both — LanguageTool keeps its key
aiCat is free to start with 10 aiCatCoins a month and does not conflict with anything else on your machine.
Frequently asked
Is aiCat a good LanguageTool alternative?
It depends on why you are looking. aiCat replaces LanguageTool for people who want one key that acts on text anywhere on the machine, in any language. It does not replace LanguageTool for grammar and style checking across thirty-odd languages, not just english, which is what LanguageTool is built around.
Is aiCat cheaper than LanguageTool?
No, not for grammar alone. LanguageTool Premium starts from about $5 a month against aiCat's $6, and its free tier does more free grammar checking than aiCat's ten coins will. The comparison turns only when you count the other tasks: if translation, explanation or dictation are also on your list, aiCat's $6 replaces two or three subscriptions and LanguageTool's $5 replaces one.
Can I use aiCat and LanguageTool together?
Yes, and it is a sensible pairing on a budget: let LanguageTool's free tier underline the typos as you type, and keep aiCat's key for the sentences where the problem is what they say rather than how they are punctuated.
What does LanguageTool do that aiCat does not?
A self-hosting story that is mature today, not a roadmap item; Very hard to beat on price for pure grammar checking; Thirty-plus languages checked by real linguistic rules rather than a model's judgement; Deterministic: the same sentence gets the same correction twice.
What is aiCat?
aiCat is a desktop app for macOS, Windows and Linux. You select text anywhere on your computer, press one hotkey, and an AI does what you need with it — proof-read, translate, explain, check the facts, read it aloud, or answer a question about it.
Does aiCat work in every application?
Yes. It works at the operating-system level rather than through per-app plugins, so it covers native apps, browsers, IDEs, terminals and PDF viewers alike.