Cloud Spell Check API

Add JSpell spell checking to your web app, mobile app or server application. The free plan includes 1,000 checks a month; paid plans raise the limit and remove the rate limit.

The API is a simple JSON endpoint: send text, and it returns each misspelled word, where it is in your text, and suggested corrections, best first. No AI: every word is checked against a dictionary and suggestions are dictionary spellings, so your users' text is never rewritten, and it never suggests offensive words.

Get Started

How it works

Send a POST request with the text, its language and the checking options. Sign-up, keys and billing are handled by RapidAPI; its README has the full reference and examples in curl, JavaScript and Java.

POST https://jspell-checker.p.rapidapi.com/check
X-RapidAPI-Key: YOUR_KEY
X-RapidAPI-Host: jspell-checker.p.rapidapi.com
Content-Type: application/json

{
  "language": "enUS",
  "fieldvalues": "Pleese check my speling before I submitt the reprot.",
  "config": {
    "forceUpperCase": false,
    "ignoreDouble": false,
    "ignoreFirstCaps": true,
    "ignoreIrregularCaps": false,
    "ignoreUpper": false,
    "ignoreWordsWithNumbers": true
  }
}

The response lists each misspelled word, where it starts, and up to 10 suggestions, best first:

{
  "elements": [
    {
      "id": 0,
      "errors": [
        { "word": "Pleese", "position": 0, "suggestions": ["Please", "Plisse", "Plissé", "Pleases", ...] },
        { "word": "speling", "position": 16, "suggestions": ["spelling", "spieling", "spellings", ...] },
        { "word": "submitt", "position": 33, "suggestions": ["submit", "submits", "subsist", ...] },
        { "word": "reprot", "position": 45, "suggestions": ["report", "reproof", "reprove", ...] }
      ]
    }
  ],
  "spellingErrorCount": 4
}

Languages

Code	Dictionary
enUS	English (US)
enGB	English (UK)
enCA	English (Canada)
enAU	English (Australia)
enUSMedical	US English plus medical terms (FDA drug names, ICD-10-CM, MeSH)
frFR	French
esES	Spanish (Spain, Latin America and the US)
enesUS	English and Spanish together (Spanglish)
deDE	German
itIT	Italian

What you get

• Each misspelled word with its position in your text, counted in characters (UTF-16, the same as JavaScript, Java and C# string indexes)
• Up to 10 suggestions per word, best first, matching the word's capitalization
• Never suggests offensive words, so it is safe for schools and businesses
• Up to 100,000 characters per request, or several separate texts (such as form fields) in one call
• Options to skip acronyms, words with numbers and repeated words, and to check text that should be all capitals
• No grammar checking and no rewriting: your users stay in control of their words

Medical terms

enUSMedical is American English plus more than 50,000 medical terms: drug names from the FDA, diagnoses from ICD-10-CM and vocabulary from the National Library of Medicine's MeSH, refreshed in October 2026. "The patient was given lisinipril for hypertention." comes back with lisinopril and hypertension as the first suggestions. Try it on the free medical spell checker.

Spanglish: English and Spanish together

With enesUS, text that mixes English and Spanish, even within a sentence, is checked against both dictionaries at once, including US Spanish words such as troca, parquear and aseguranza. A word is reported only if it is wrong in both languages, and its suggestions come from both. "Voy a parquear la troca y después vamos al mall to grab lunch." has no errors. Try it on the free Spanglish spell checker.

Plans

BASIC is free for 1,000 checks a month (rate limited). PRO, ULTRA and MEGA include 10,000, 50,000 and 300,000 checks a month with no rate limit. Current prices are on the RapidAPI pricing page. For more than 1 million checks a month, or to include JSpell in a product you sell, contact us.

Privacy and hosting

Text is checked and then discarded: it is never stored or logged, and never used to train AI. The checks run on Cloudflare's global network, close to your users, with the same dictionaries as the JSpell software products. RapidAPI handles sign-up, billing and usage tracking.

Need text to stay on your own servers, for example patient data? The JSpell SDKs and server products run entirely on your own servers.

For AI agents

RapidAPI also offers the API as an MCP tool named check, so AI assistants and agents can check spelling with dictionary suggestions instead of rewriting text.

Spell check API FAQ