GrammarChecker: An Instant Grammar Correction Tool Based on Large Language Models

GrammarChecker is a desktop grammar correction tool based on Large Language Models (LLM). It supports global shortcut key activation and can instantly correct grammar errors in any text input box. It integrates mainstream LLM APIs such as OpenAI and Gemini, is developed based on the Qt framework, provides a native-level user experience, and aims to offer professional text polishing services without interrupting the user's workflow.

Traditional grammar checking tools have problems such as cumbersome copy-pasting and limited browser plugin support. The design concept of GrammarChecker comes from an understanding of real-world scenarios: users do not need to leave their current working environment—after selecting text, they can press a shortcut key to call AI grammar correction, avoiding the interference of application switching.

Driven by Large Language Models

Supports OpenAI API (GPT series), Google Gemini API, and custom compatible models, allowing users to flexibly choose service providers.

Cross-Platform Implementation

Based on the Qt 6.8 framework, it has advantages such as native performance, system tray integration, global shortcut key monitoring, low resource usage, and fast response.

Dependent Libraries

Uses mature open-source libraries like liboai (OpenAI communication), nlohmann-json (JSON processing), and curl (network transmission) to build core functions.

Functional Features

• Instant correction: Select text and press a shortcut key to complete correction and replace the original text within seconds;
• Customizable prompts: Supports extended functions such as multi-language translation, style adjustment, content expansion, and summary extraction;
• System integration: Auto-start on boot, run in the system tray, and provide an intuitive configuration interface (API key management, shortcut key settings, etc.).

Application Scenarios

Suitable for scenarios like business email writing, technical document preparation, instant messaging communication, and academic paper polishing—especially helpful for non-native English speakers to improve the professionalism of their expression.

• Global Shortcut Keys: Register system-level hotkeys via Qt QHotkey or Windows API to ensure triggering in any application;
• Text Injection: Simulate keyboard input to replace selected content, compatible with most text input scenarios;
• API Error Handling: Implement network timeout retries, rate limit handling, and friendly prompts to ensure stability.

GrammarChecker uses the GPL-3.0 open-source license. The code is transparent and reviewable, supporting free modification and secondary development. Community members are welcome to submit Issues and Pull Requests to jointly improve the tool and provide privacy and security guarantees for users.

Current Limitations

• API dependency: Requires OpenAI/Gemini keys; domestic users may face network access issues;
• Platform limitations: Mainly supports Windows; macOS/Linux versions are under development;
• Offline capability: Relies on cloud services and cannot be used offline.

Future Directions

• Integrate local LLMs (such as Llama, Mistral) to implement offline functions;
• Expand to macOS/Linux platforms;
• Build a plugin ecosystem and prompt template market;
• Support batch processing of entire documents.

GrammarChecker does not replace human writing; instead, it integrates seamlessly into existing workflows to provide instant intelligent assistance. It helps users improve writing efficiency and expression quality, demonstrating the possibility of AI technology being elegantly integrated into daily scenarios—especially valuable for users who frequently write in English.