Writetone HumanGPT is a good one. It can convert AI-generated text into human-sounding text that passes GPTZero, Originality.ai and Turnitin tests. Built-in AI detector lets you check your content to make sure it'll pass the human test. It also can help you select the best tone and perspective with multiple drafts, so it's good for maintaining a natural voice while optimizing your writing.
Another tool worth a look is NetusAI, which offers a collection of tools to generate content that's not flagged by plagiarism and AI content detectors. It's got tools for paraphrasing, summarizing and an AI detector that'll let you check your work to make sure it's not a duplicate. It works in multiple languages and lets you customize AI models, too, so NetusAI could be good for digital marketing, blogging and other writing tasks.
If you want something more straightforward, Undetectable AI is a good option. The tool rewrites text to sound more like human writing, improving vocabulary, grammar and sentence structure. It also has an SEO optimization option and an easy-to-use interface, so you can generate engaging, undetectable content with no registration or limits.