Harper

Harper is an open-source desktop app and a browser extension that provides English grammar checking. It operates as a browser extension that analyzes writing directly on the user's device to ensure data privacy. The tool is designed for individuals who want to correct their writing without sending sensitive text to external servers for processing.

The software is deployed as a browser extension and utilizes WebAssembly to maintain a small memory footprint and low latency during the analysis process. It targets a middle ground between heavy, resource-intensive local tools and cloud-based services that may compromise user data. By running the logic locally, the extension avoids the network requests and round-trip times that often slow down the revision process.

Key features

• Local processing of text to keep data private on the device
• English language grammar checking
• WebAssembly implementation for fast loading
• Low memory usage compared to n-gram based checkers
• Millisecond response times for document linting
• Extensible core for future language support
• Integration with supported web-based editors

The technical architecture leverages Rust and WebAssembly to achieve high performance and efficiency. This approach allows the software to perform linting in milliseconds while requiring significantly less RAM than traditional local grammar checkers that rely on massive n-gram datasets. The project is built using a stack that includes React, Svelte, and Node.js, ensuring that the interface remains responsive while the core engine handles the linguistic analysis.

This tool is intended for writers, developers, and professionals who require a fast, local English grammar checker. It is specifically aimed at those who find cloud-based services too invasive regarding privacy or too expensive in terms of subscription costs. By prioritizing performance, the project treats long linting times as bugs to be fixed.

Harper is a lightweight, privacy-focused utility for English writing correction.