LanguageTool Proofreading API

Join 100+ companies and enhance your software with our HTTP API

Get developer access to the same technology that powers our Premium grammar, style and spelling checker. It supports more than 20 languages, including English, French, Spanish and German. The API can easily be used from any programming language, since it's based on HTTP and returns simple-structured JSON data.

per month

You need more API calls per day or need help? Just contact us!

all prices incl. VAT
can be cancelled any month


  • All servers are hosted in Germany, the service is fully GDPR-compliant
  • None of the texts you send to the API are stored to ensure full privacy
  • An on-premise version is available - contact us for details
  • Monthly plans can be cancelled any month
  • Maximum text length per request: 60,000 characters (contact us if you need more)
  • Specific grammar or style rules can be disabled to meet individual requirements
  • The personal dictionary is also available through the API
Show API documentation