LanguageTool

aid: languagetools
name: LanguageTool
description: >-
  Open-source grammar, style, and spell checking REST API supporting 25+
  languages with AI-powered error detection, style suggestions, and text
  improvements. Used by 100+ companies to enhance software with proofreading
  capabilities via a simple HTTP API returning JSON responses. Hosted on
  GDPR-compliant servers in Germany with no text storage.
image: https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
url: >-
  https://raw.githubusercontent.com/api-evangelist/languagetools/refs/heads/main/apis.yml
created: '2026-06-13'
modified: '2026-06-13'
specificationVersion: '0.19'
type: Index
tags:
  - Grammar
  - Spell Check
  - Style
  - Proofreading
  - NLP
  - Natural Language Processing
  - Writing
  - Open Source
apis:
  - aid: languagetools:languagetool-api
    name: LanguageTool Proofreading API
    description: >-
      HTTP REST API for grammar, style, and spell checking across 30+ languages.
      Accepts POST requests with text and language parameters, returning JSON
      with detected errors, suggestions, and rule matches. Supports up to 60,000
      characters per request with optional API key authentication for premium
      tiers.
    image: >-
      https://kinlane-productions.s3.amazonaws.com/apis-json/apis-json-logo.jpg
    humanURL: https://languagetool.org/http-api/
    baseURL: https://api.languagetool.org/v2
    tags:
      - Grammar
      - Spell Check
      - Proofreading
      - Style
      - NLP
    properties:
      - type: Documentation
        url: https://languagetool.org/http-api/
      - type: OpenAPI
        url: https://raw.githubusercontent.com/api-evangelist/languagetools/main/openapi/openapi.json
common:
  - type: Website
    url: https://languagetool.org
  - type: Documentation
    url: https://languagetool.org/http-api/
  - type: GitHubOrg
    url: https://github.com/languagetool-org
  - type: LinkedIn
    url: https://www.linkedin.com/company/languagetool
  - type: Blog
    url: https://languagetool.org/insights/
  - type: Pricing
    url: https://languagetool.org/proofreading-api
  - type: X
    url: https://x.com/languagetoolorg
  - type: Plans
    url: https://raw.githubusercontent.com/api-evangelist/languagetools/refs/heads/main/plans/plans.yml
  - type: RateLimits
    url: https://raw.githubusercontent.com/api-evangelist/languagetools/refs/heads/main/rate-limits/rate-limits.yml
  - type: FinOps
    url: https://raw.githubusercontent.com/api-evangelist/languagetools/refs/heads/main/finops/finops.yml
maintainers:
  - FN: Kin Lane
    email: [email protected]