NextChat

Zero-config AI chat assistant. No API key needed — sign up and instantly chat with GPT-5, Claude 4, Gemini 2.5, DeepSeek & 100+ top models. Pay-as-you-go saves you more. Available on Web, iOS, macOS, Android, Linux, Windows. Maintained by ChatGPTNextWeb on GitHub, where it has earned 88,714 stars from the community.

It's actively developed around chatgpt, nextjs, vercel, and is a solid reference for anyone building with these tools.