Check grammar
A single misplaced comma or subject-verb mismatch can undercut an otherwise solid piece of writing, and catching those errors across dozens of languages is not a job most teams can staff. The Grammar Checker API scans submitted text, corrects grammatical errors, agreement, punctuation and syntax across more than 30 languages, and returns clean copy without altering tone, vocabulary or meaning. It corrects; it does not rewrite.
Run it online
Run this on our servers with your account. Free tools run in your browser; this one bills your KIT balance per the price above.
Why grammar checking still needs automation at scale
Any team publishing content in more than one or two languages eventually hits a wall: proofreaders fluent in every target language are expensive, slow to schedule, and hard to keep consistent across a large content volume. A programmatic grammar checker fills that specific gap, not replacing an editor's judgment on style, but catching the mechanical errors, wrong verb conjugations, missing articles, punctuation slips, that slip past a tired writer regardless of language.
What correction means here, specifically
The engine fixes what is objectively wrong: subject-verb agreement, gender and number agreement where the language requires it, verb tense consistency, punctuation placement and spelling. It does not rewrite sentence structure for style, does not change your word choice, and does not adjust tone; a grammatically flawed but stylistically deliberate sentence keeps its style and loses only its errors. That distinction is what separates a grammar checker from a general rewriting tool.
Language coverage and how it is structured
The 30-plus supported languages span the Romance, Germanic and Slavic families along with several major Asian languages, covering the language set most international content teams actually publish in. Each request specifies or lets the engine detect the source language, and correction rules are applied according to that language's own grammar, not translated rules borrowed from English.
The mechanics of a request
Call POST /text/grammar with the text to check; the task is queued and a task_id returns immediately so the call never blocks your application. Processing happens asynchronously, and the corrected text arrives through a signed webhook the moment it is ready, or through a signed link you can fetch for up to 24 hours afterward. A brief history of the format: language checkers as a category trace back to rule-based spell checkers of the 1970s and 80s; this endpoint applies grammar rules with the flexibility that fixed rule tables never had, without abandoning the precision those older tools were built for.
Built for pipelines, not single documents
Content management systems can run every article through the endpoint on save, translation workflows can grammar-check the target language after machine translation, and customer support platforms can clean outgoing replies before they are sent, all without a human proofreader in the loop for routine cases. Automatic retries handle transient failures up to three times, a task that ultimately fails is never billed, and there is no free tier by design, keeping the endpoint responsive for metered, production use.
What you can do with it
Post-translation grammar pass
A localization pipeline runs machine-translated text through the grammar checker in the target language before it reaches a human reviewer, cutting the number of trivial fixes they have to make.
Outgoing support replies
A helpdesk grammar-checks every agent reply in real time before sending, catching errors in a fast-paced, high-volume queue where a second human pass is not realistic.
Multilingual content publishing
A media company checks grammar across articles published in a dozen languages without hiring a dedicated proofreader fluent in each one.
User-generated content moderation
A marketplace cleans up grammar in seller-written product listings so storefronts read professionally regardless of the seller's native language.
FAQ
How many languages does the grammar checker support?
More than 30 languages across the Romance, Germanic, Slavic and major Asian language families, each corrected according to its own grammar rules.
Is the grammar checker API free?
There's no free tier — free tiers get abused and slow everyone down. Access runs on a prepaid ForHosting KIT balance: top up from $10.00 (it never expires) and each request is charged at its published price, so a call with no balance returns HTTP 402. No subscription, no tokens, no invented credits, and a failed task is never charged.
How much does grammar checking cost?
$0.003 per request plus $0.0135 per 1,000 words, and you are billed only when a task completes successfully.
Does it change my writing style or word choice?
No, it corrects objective grammatical errors, agreement, tense and punctuation, without rewriting style, vocabulary or tone.
Can it check very large documents or many files at once?
Yes, since every call is asynchronous with its own task_id, you can submit large volumes and collect each result independently as it completes.
How is this different from a spell checker?
A spell checker only flags misspelled words; this endpoint corrects grammar, agreement, syntax and punctuation, a broader and more structural class of error.
How do I get the corrected text back?
Through a signed webhook call when the task finishes, or a signed link valid for 24 hours, after which the submitted data is deleted.
What happens if a grammar check request fails?
The system retries automatically up to three times; if it still fails, you receive a clear error and are never charged for it.
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, and soon from our app, email and Telegram.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/text/grammar \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"text":"…"}'const res = await fetch("https://api.kit.forhosting.com/text/grammar", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"text": "…"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/text/grammar",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"text": "…"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/text/grammar", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"text":"…"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"text":"…"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/text/grammar", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"text": "…"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "text.grammar",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_tokens | 20000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
422 | task_failed | The task failed after 3 retries. You are never charged for it. |