Jan (43,864 Stars) 2026: The Offline-First AI Assistant Desktop App - Run Models Locally with OpenAI-Compatible API

Jan (43,864 stars) is the offline-first AI assistant for desktop - run open-source models locally with a clean UI and an OpenAI-compatible local API. Here is the complete guide.

💡 What You Will Learn

Jan (43,864 stars) is the offline-first AI assistant for desktop - run open-source models locally with a clean UI and an OpenAI-compatible local API. Here is the complete guide.

📜 Table of Contents

• The short answer
• Why Jan stands out
• Getting started
• Using the local API
• Practical tips
• FAQ

The short answer

janhq/jan (43,864 stars, TypeScript) is an offline-first AI assistant desktop app. You install it, download a model, and chat - fully offline. It also exposes an OpenAI-compatible local API server, so other tools (like Open WebUI or your scripts) can use the same local models.

Why Jan stands out

• Offline-first: models run 100% on your device
• Clean desktop UI: Windows, macOS, Linux
• Model hub: browse and download GGUF models in-app
• Local API: OpenAI-compatible endpoint for integrations
• Extensions: add tools and features via Jan extensions

Getting started

1. Download Jan from https://jan.ai (Windows/macOS/Linux).
2. Open the app and go to the Model Hub.
3. Download a model (start with a 3B-8B quantized GGUF).
4. Start a conversation - it runs offline, no account needed.

Using the local API

Enable the local API server in settings, then:

curl http://localhost:1337/v1/chat/completions \n  -H "Content-Type: application/json" \n  -d '{"model": "llama3.2", "messages": [{"role": "user", "content": "Hello"}]}'

Any OpenAI-compatible client can now talk to your local models.

Practical tips

• Try the extension marketplace for connectors (e.g. to cloud models when needed).
• Keep the app updated - inference performance improves with each release.
• For heavier models, close other apps or use a machine with 16 GB+ RAM.

FAQ

Is it free? Yes - open source (AGPL for the app).

Does it need a GPU? No - it runs on CPU, and uses GPU when available.

Can I use it as a local OpenAI replacement? Yes - the built-in API server makes it drop-in compatible with OpenAI SDKs.

❓ FAQ

Is it free?

Yes - open source (AGPL for the app).

Does it need a GPU?

No - it runs on CPU, and uses GPU when available.

Can I use it as a local OpenAI replacement?

Yes - the built-in API server makes it drop-in compatible with OpenAI SDKs.