1. Grammarly: Grammarly is a popular writing assistant tool that helps improve grammar, spelling, punctuation, and style. It provides suggestions and corrections in real-time, making it a great tool for enhancing your writing.

2. Hemingway Editor: Hemingway Editor is a tool that helps you simplify and improve your writing style. It highlights complex sentences, excessive adverbs, and passive voice, allowing you to make your writing more concise and clear.

3. ProWritingAid: ProWritingAid is a comprehensive writing tool that offers grammar and spelling checks, style suggestions, readability analysis, and more. It also provides detailed reports on your writing, helping you identify areas for improvement.

4. Ginger: Ginger is a writing tool that offers grammar and spell-checking, sentence rephrasing, and translation features. It also provides a personal trainer feature that helps you learn from your mistakes and improve your writing skills.

5. LanguageTool: LanguageTool is an open-source grammar and style checker that supports multiple languages. It offers suggestions for grammar, spelling, punctuation, and style errors, making it a versatile tool for writers.

6. WhiteSmoke: WhiteSmoke is a writing assistant tool that offers grammar and spell-checking, style suggestions, and plagiarism detection. It also provides a translator feature, making it useful for non-native English speakers.

7. AutoCrit: AutoCrit is a writing tool specifically designed for fiction writers. It analyzes your writing for areas such as pacing, dialogue, word choice, and repetition, helping you improve the overall quality of your manuscript.

8. Slick Write: Slick Write is a free online writing tool that offers grammar and style suggestions. It provides real-time feedback on your writing, highlighting errors and offering suggestions for improvement.

These tools can be used alongside or as alternatives to QuillBot, depending on your specific writing needs and preferences.