Jan

Jan is a free, open-source local AI assistant software that can serve as an offline replacement for ChatGPT. The core difference is that Jan runs entirely on the user's local device without internet access, ensuring data privacy; ChatGPT, by contrast, is a cloud-based service. Jan primarily supports text dialogue and its features are comparatively focused.

Jan supports multiple open-source models (such as LLaMA, Mistral, Gemma, in GGUF format) and can connect to cloud services like OpenAI, Anthropic, Google via API. It also includes its own in-house Jan-V1-4B model, which excels at reasoning and tool invocation.

Jan supports CPU and GPU acceleration (including NVIDIA and Apple M-series chips). Actual performance depends on the model size; smaller models (e.g., 4B parameters) can run on a normal PC, while larger models require more RAM and VRAM.

Jan is completely free and open source. You can download desktop applications for macOS, Windows, or Linux from its official website or GitHub and install them; no registration or paid subscription is required.

The core advantage is on-device offline operation. All conversations and data processing occur on your device and are not uploaded to any remote servers, fundamentally protecting data privacy and user control.

The Jan interface currently primarily supports English, but most of the open-source models it supports (such as Qwen, DeepSeek, etc.) have strong Chinese understanding and generation capabilities, so you can converse in Chinese.