LanguageTool is a grammar, style, and spelling checker from Germany. The software is open source and they offer client for many clients.
European spelling and grammar checkers
A spelling and grammar checker helps authors to check their texts for spelling and grammar errors.
This category contains services from companies based in a member state of the European Union (EU), the European Economic Area (EEA) and the European Free Trade Association (EFTA).
You can read more about the listing criteria here.
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