Jan is an open-source (Apache-2.0) desktop application, first released in 2023 and maintained by Menlo Research, that positions itself as a private, offline alternative to ChatGPT. It downloads and runs open-source models locally through a built-in model hub, stores chat history on-device, and can also connect out to cloud providers like OpenAI, Anthropic and Google when you want them — all from one interface. With 43k+ GitHub stars and millions of downloads, it has a sizable community.
A defining feature is its built-in OpenAI-compatible API server (on port 1337), which lets other tools and IDEs use Jan as a local LLM backend. Built with Tauri, it runs across macOS, Windows and Linux and supports GPU acceleration as well as CPU-only inference. It is less polished than some commercial GUIs and a handful of advanced features are still in progress, but the privacy story and openness are strong.
Key Benefits
- Open and free: Apache-2.0 with no usage caps — you own the stack.
- Offline-first privacy: Conversations and inference stay on your device by default.
- Local API backend: The OpenAI-compatible server turns Jan into infrastructure other apps can call.
- One interface, many models: Switch between local and major cloud models without leaving the app.
Use Cases
- Private daily assistant — A ChatGPT-style experience that runs without sending data to the cloud.
- Local backend for tools — Use Jan's server as a drop-in OpenAI endpoint for IDEs and scripts.
- Hybrid local/cloud workflows — Default to local models and reach for a frontier API only when needed.
- Learning local LLMs — A friendly GUI for downloading and comparing open models.