API stands for Application Programming Interface. It's a way for different software applications to talk to each other. The API lets developers connect their apps to LanguageTool's services without needing to open a browser or use the LanguageTool website. So if you're building a writing tool, chatbot, or even an editor, the API is how you “plug in” LanguageTool’s language-checking powers.
LanguageTool offers both public and premium APIs for grammar, style, and spelling checks across multiple languages. For higher usage needs, LanguageTool offers premium API plans with increased request limits and additional features. Pricing details can be found here. Premium plans also provide higher request limits and more advanced features.
The daily request limit depends on the plan
Maximum number of requests per minute: 20 (free) / 80 (Premium)
Maximum number of characters per minute: 75,000 (free) / 300,000 (Premium)
Maximum number of characters per request: 20,000 (free) / 60,000 (Premium)
Self-Hosted API
Alternatively, users can set up their LanguageTool server to have full control over the API usage. Detailed instructions are available on the LanguageTool development site, which can be found here.