Harper is a local English linter and grammar checker designed as an IDE writing assistant. It operates as a language server that provides real-time spelling and grammar analysis for markdown and code comments, processing all linguistic data on the local device to ensure privacy and eliminate cloud dependencies.
The tool is specialized for technical documentation, featuring the ability to identify and ignore text within code fences and inline blocks to prevent false positives. It allows for personalized configuration through custom dictionaries and the use of suppression comments to exclude specific text regions from analysis.
The system provides actionable diagnostic mapping that enables quick-fix error resolution and grammar fix applications directly within a text editor.