AI Grammar Checker

QuillBot is a web-based AI writing platform that integrates paraphrasing, grammar checking, plagiarism detection, AI humanization, citation generation, and PDF conversion into a single tool suite. It operates on a freemium model with a Premium upgrade tier and includes experimental features such as an AI Image Generator and AI Chat alongside its core writing modules.

Grammarly is an AI-powered writing assistant that deploys specialized agents for grammar checking, citation finding, AI-content detection, assignment grading, and audience feedback simulation across applications and browser tabs.

Youdao Writing is an AI-powered English writing assistant for Chinese users, offering grammar, spelling, and style correction.

Pretty Prompt is a browser extension and web application that helps users improve their AI prompts by transforming casual text into structured, effective instructions. Launched on Product Hunt as version 1.0, it offers a freemium model with a Pro tier unlocking unlimited prompts, full history, a saved library, and advanced features. While the core proposition is accessible, several documentation and developer resource pages were unavailable at review time.