LanguageTool website screenshot

LanguageTool

LanguageTool is an open-source proofreading and grammar checking tool that supports more than 25 languages. The HTTP API enables developers to programmatically check texts for grammar and style issues, list supported languages, and manage personal dictionaries.

LanguageTool publishes 3 APIs on the APIs.io network: Check API, Languages API, and Words API. Tagged areas include Grammar, Language, Proofreading, Spell Check, and Style Check.

The LanguageTool catalog on APIs.io includes 1 Spectral governance ruleset.

LanguageTool’s developer surface includes documentation, GitHub presence, and 7 more developer resources.

🌐 Visit website 📡 Source on GitHub
47.2/100 developing ▬ flat Agent 25/100 agent aware Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessFreemium
3 APIs
GrammarLanguageProofreadingSpell CheckStyle CheckText Analysis

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 47.2/100 · developing
Contract Quality 14.1 / 25
Developer Ergonomics 1.7 / 20
Commercial Clarity 12.1 / 20
Operational Transparency 4.8 / 13
Governance 7.0 / 12
Discoverability 7.4 / 10
Agent readiness — 25/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
MCP Server 0 / 12
Machine-Readable Auth 0 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 7 / 7
Rate-Limit Signaling 7 / 7
Typed Event Surface 0 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/languagetool: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 3

Individual APIs this provider publishes, each with its own machine-readable definition.

LanguageTool Check API

The Check API from LanguageTool — 1 operation(s) for check.

LanguageTool Languages API

The Languages API from LanguageTool — 1 operation(s) for languages.

LanguageTool Words API

The Words API from LanguageTool — 3 operation(s) for words.

Open Collections 1

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

LanguageTool HTTP API

OPEN COLLECTION

Pricing Plans 1

Published pricing tiers and plan structures.

Languagetool Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Languagetool Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Languagetool Finops

FINOPS

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

LanguageTool API Rules

5 rules · 3 warnings 2 info

SPECTRAL

JSON Schema 1

Standalone JSON Schema definitions for this provider's data models.

LanguageTool Match

8 properties

JSON SCHEMA

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Languagetool Domain Security

TLSv1.3 · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Languagetool Agentic Access

5 operations · 3 acting

5 operations · 3 acting

AGENTIC

Resources

Documentation 1

Reference material describing how the API behaves

Documentation
Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess
AgenticAccess

Build 1

SDKs, sample code, and the tooling you integrate with

GitHub
GitHub

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity

Commercial 2

Pricing, plans, and the legal terms of use

PrivacyPolicy
PrivacyPolicy
 TermsOfService
TermsOfService

Company 2

The organization behind the API

LinkedIn
LinkedIn
 Website
Website

Other 1

Properties that don't map to a standard resource type

Developer
Developer

Source (apis.yml)

apis.yml Raw ↑ 
aid: languagetool
name: LanguageTool
description: LanguageTool is an open-source proofreading and grammar checking tool that supports more than 25 languages. The
  HTTP API enables developers to programmatically check texts for grammar and style issues, list supported languages, and
  manage personal dictionaries.
type: Index
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
position: Consumer
access: 3rd-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/languagetool.png
tags:
- Grammar
- Language
- Proofreading
- Spell Check
- Style Check
- Text Analysis
created: '2025-02-08'
modified: '2026-05-19'
url: https://raw.githubusercontent.com/api-evangelist/languagetool/refs/heads/main/apis.yml
specificationVersion: '0.19'
apis:
- aid: languagetool:languagetool-check-api
  name: LanguageTool Check API
  description: The Check API from LanguageTool — 1 operation(s) for check.
  humanURL: https://languagetool.org/http-api/
  baseURL: https://api.languagetool.org/v2
  tags:
  - Check
  properties:
  - type: OpenAPI
    url: openapi/languagetool-check-api-openapi.yml
  - type: Documentation
    url: https://languagetool.org/http-api/
  - type: SwaggerUI
    url: https://languagetool.org/http-api/swagger-ui/
  - type: JSONSchema
    url: json-schema/languagetool-match-schema.json
- aid: languagetool:languagetool-languages-api
  name: LanguageTool Languages API
  description: The Languages API from LanguageTool — 1 operation(s) for languages.
  humanURL: https://languagetool.org/http-api/
  baseURL: https://api.languagetool.org/v2
  tags:
  - Languages
  properties:
  - type: OpenAPI
    url: openapi/languagetool-languages-api-openapi.yml
  - type: Documentation
    url: https://languagetool.org/http-api/
  - type: SwaggerUI
    url: https://languagetool.org/http-api/swagger-ui/
  - type: JSONSchema
    url: json-schema/languagetool-match-schema.json
- aid: languagetool:languagetool-words-api
  name: LanguageTool Words API
  description: The Words API from LanguageTool — 3 operation(s) for words.
  humanURL: https://languagetool.org/http-api/
  baseURL: https://api.languagetool.org/v2
  tags:
  - Words
  properties:
  - type: OpenAPI
    url: openapi/languagetool-words-api-openapi.yml
  - type: Documentation
    url: https://languagetool.org/http-api/
  - type: SwaggerUI
    url: https://languagetool.org/http-api/swagger-ui/
  - type: JSONSchema
    url: json-schema/languagetool-match-schema.json
common:
- type: AgenticAccess
  url: agentic-access/languagetool-agentic-access.yml
- type: DomainSecurity
  url: security/languagetool-domain-security.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/languagetool
- type: Website
  url: https://languagetool.org
- type: Documentation
  url: https://languagetool.org/http-api/
- type: Developer
  url: https://dev.languagetool.org/
- type: GitHub
  url: https://github.com/languagetool-org/languagetool
- type: PrivacyPolicy
  url: https://languagetool.org/legal/privacy
- type: TermsOfService
  url: https://languagetool.org/legal/terms
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com