Chinese developers have replaced GPT-5 with the open-source model Kimi K2 Thinking. This model not only competes with GPT-5 and Sonnet 4.5 but also excels in tool calling, such as executing Python code and browsing functionalities.

Kimi K2 is impressive as it can handle up to 300 consecutive requests to tools, breaking down tasks into subtasks efficiently. Users can test the model on the Kimi website, with the model itself available on Hugging Face for further exploration.