If you're looking for a MindMac alternative, ChatTab is a good choice. This native macOS desktop app connects to OpenAI's ChatGPT API, so you can use multiple models like GPT3.5 and GPT4-Vision without logging in separately. ChatTab has a different interface with multiple tabs, Markdown support, customizable keyboard shortcuts and iCloud sync. It stores API keys securely and supports multiple languages, and there are free, Pro and Max plans with different levels of features and tokens.
Another option is MacGPT, which builds ChatGPT directly into your Mac's menubar. It has four modes: Global, Inline, Menubar and Web/Native, and supports conversation mode for voice prompts. MacGPT integrates with an iPhone app so you can use it on your phone, too. The software works on macOS Monterey and Ventura and supports ChatGPT Plus accounts and OpenAI API keys, though some features are limited by API limits.
If you want a more conversational interface, WriteMage could be a good choice. This AI-powered tool builds ChatGPT into your macOS and iOS devices so you can use it in any app without having to copy and paste. WriteMage includes a local chat history, customizable prompt editor and native integration with the iOS keyboard. It offers a Basic plan for two devices and a Personal plan with more features, and for now, a one-time lifetime deal during the beta test.