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SiteCheck Grammar Checker
x402
SiteCheck Grammar Checker is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-16).
Checks text for grammar and spelling errors, returning annotated issues with suggestions and a corrected version, powered by LanguageTool
Price / call$0.002
Success—
StatusUnknown
How this service works
Grammar, spelling and style check with LanguageTool: each issue with its message, the offending text, its position, up to five suggestions, the rule id and category, plus the corrected text with the first suggestion of each issue applied. Body { text, language }: up to 20 KB, language auto by default. Text is sent only to LanguageTool's public API.
Output
Returns a JSON object with a count of issues found, an array of issue objects (each with the bad text, its character offset and length, the LanguageTool rule ID, a human-readable message, the error category, and an array of suggested corrections), the detected or specified language, the source API, the timestamp, and a fully corrected version of the input text.
Example use cases
Proofread outgoing customer email
“Before I send this support reply, check it for grammar errors in US English: 'Thank you for reaching out. We has reviewed your case and our team are working on a solution.'”
Validate multilingual marketing copy
“Check this French marketing text for grammar issues: 'Nous sommes ravis de vous presentez notre nouvelle produit.' Use fr as the language.”
Auto-proofread user-generated content
“A user just submitted this product review and I want to flag any grammar problems before it goes live: 'The battery life are amazing but the screen have some scratches out of box.' Check it in en-US and show me what needs fixing.”
Technical details
Endpoint
POSThttps://api.sitecheck-api.workers.dev/api/text/grammar?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need rule-based grammar and spelling validation with detailed per-error annotations (offset, rule ID, category, suggestions) and an auto-corrected output. It is particularly useful for agents automating content pipelines, proofreading user-generated text, or validating copy before publishing. It supports multiple languages via LanguageTool, making it suitable for multilingual workflows. Prefer it over LLM-based rewriting when you need structured, auditable error reports rather than a free-form rewrite.
Side effects
- Text exceeds 20 KB limit — request rejected
- Unsupported language code returns an error or falls back to auto-detection
- Malformed JSON body causes a 400 error
- LanguageTool upstream API unavailable causes a 502 or timeout
- Empty text field returns zero issues or an error
- Network or payment (x402) failure prevents the call from completing
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| text | string | The text to check, up to 20 KB (JSON body field) |
| language | string | auto (default), en-US, en-GB, de-DE, fr, es, pt-BR ... as LanguageTool supports them |
Output
Schema · Response
{
"type": "json",
"example": {
"count": 2,
"issues": [
{
"bad": "has",
"length": 3,
"offset": 2,
"ruleId": "BASE_FORM",
"message": "Possible agreement error — use the base form here.",
"category": "GRAMMAR",
"suggestions": [
"have"
]
},
{
"bad": "sleep",
"length": 5,
"offset": 16,
"ruleId": "IT_VBZ",
"message": "After ‘It’, use the third-person verb form “sleeps”.",
"category": "GRAMMAR",
"suggestions": [
"sleeps"
]
}
],
"source": "LanguageTool public API (api.languagetool.org)",
"language": "en-US",
"checkedAt": "2026-10-15T13:48:02.031Z",
"corrected": "I have a cat. It sleeps all day."
}
}Tags
x402
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