What Jan Actually Does

Jan is desktop software that runs AI models locally on your computer. Think ChatGPT but the processing happens on your hardware instead of sending everything to OpenAI's servers. Built by Menlo Research, a team that got tired of privacy-destroying AI services, it's actually open source and works completely offline once you download the models.

I've been testing Jan for a few months on my M1 Mac and here's the reality: it works pretty well for basic chat tasks, but don't expect GPT-4 level performance from models that fit on consumer hardware. The setup is surprisingly smooth on Mac, but Windows users seem to get fucked by driver issues based on the GitHub issues.

What Actually Works

Jan runs on llama.cpp under the hood, which is solid tech that's been battle-tested by the community. It supports GGUF model files from Hugging Face - thousands of them. You download models once and they stay on your machine.

The current version is 0.6.9 - dropped August 28th, 2025. Finally includes some features that aren't just marketing bullshit:

Jan AI Interface

Their own model Jan-v1 actually hits 91.1% on SimpleQA benchmarks, which shocked me for a 4B parameter model. But SimpleQA is just factual stuff - don't expect GPT-4 level reasoning. Your mileage varies wildly depending on what hardware shit you've got running in the background.

Hardware Reality Check

Don't bother unless you have:

  • At least 8GB RAM (16GB for anything useful)
  • Decent CPU or dedicated GPU
  • 10GB+ free storage per model

Runs great on:

  • Apple Silicon Macs (M1/M2/M3)
  • NVIDIA RTX cards with enough VRAM
  • Recent AMD GPUs (though support is shakier)

Pain in the ass on:

  • Integrated graphics
  • Old hardware
  • Linux with AMD cards (driver hell)

I get about 25-30 tokens/second on my M1 with the 7B Llama models, which is fast enough for real conversation. Your ancient laptop probably won't cut it.

The MCP Integration Thing

Jan supports Model Context Protocol which lets the AI actually interact with tools instead of just chatting. I've tried a few:

  • Jupyter integration works but is finicky
  • Browser automation through various services
  • Search tools that actually work

Half the MCP tools are half-baked demos, but the concept is solid and some actually save time.

Jan vs Other Local AI Tools (Reality Check)

Feature

Jan

LM Studio

Ollama

GPT4All

Interface

Decent GUI

Better GUI

CLI only

Basic GUI

Installation Pain

Medium (Mac easy, Windows pain)

Easy everywhere

Easy everywhere

Windows focused

Model Support

GGUF + cloud fallback

GGUF only

GGUF only

Their own format

Performance

Good on Mac, meh elsewhere

Consistent

Fastest

Slowest

Tool Integration

MCP (when it works)

Basic API

API only

Limited

Stability

Breaks on updates

Rock solid

Never crashes

Pretty stable

Windows Experience

Shitty

Good

Good

Best

Memory Usage

Eats RAM

Efficient

Most efficient

Bloated

Error Messages

Useless

Helpful

Clear

Decent

Community Support

Growing

Large

Huge

Moderate

What You Actually Get vs What Sucks

Installation: Smooth on Mac, Pain Elsewhere

Installing Jan on macOS is shockingly painless - download the DMG, drag to Applications, done. I had it running in 2 minutes. Windows is where everything goes to absolute shit. Half the GitHub issues are Windows users getting ENOENT errors because some random Visual C++ dependency is missing or corrupted.

Linux users get the full experience of compiling dependencies and fighting with CUDA drivers. The AppImage works sometimes, the .deb package works other times. It's a crapshoot.

Common installation fuckups I've seen:

Performance Numbers From Real Hardware (Not Synthetic Benchmarks)

Jan Performance Demo

I spent 3 weeks testing Jan across different hardware configs. Here's the reality:

MacBook Pro M1 (16GB):

RTX 4060 Desktop (16GB RAM):

Old Intel laptop (8GB):

  • Don't even bother with anything bigger than 3B models
  • Expect 5-8 tokens/sec if you're lucky

The 91.1% SimpleQA accuracy for Jan-v1 checks out - I ran the same tests myself. But SimpleQA is just factual Q&A shit like "What year did WWII end?" Don't expect complex reasoning or code that actually compiles.

MCP Tools: Hit or Miss

MCP Integration

The Model Context Protocol integration is Jan's killer feature, but implementation quality varies wildly:

Actually useful:

Half-baked demos:

Setting up MCP requires editing JSON config files manually. There's no GUI for it, which is stupid for a desktop app trying to be user-friendly.

What Jan Gets Right

Privacy: Everything runs locally when you want it to. Your conversations don't leave your machine unless you explicitly connect to cloud providers.

API Server: The localhost:1337 OpenAI-compatible server is actually solid. You can point any OpenAI client at it and it works. Great for integrating with tools like Continue.dev in VS Code or Cursor.

Model Management: Downloading and switching between models is surprisingly smooth. The interface shows download progress and storage requirements upfront.

What Pisses Me Off

Model Discovery: Finding good models requires browsing Hugging Face yourself. The built-in hub is limited and doesn't surface the best community models.

Error Messages: When something breaks, you get useless errors like "Model failed to load" with no details about why.

Memory Management: Jan's memory handling is dogshit. It doesn't unload models when switching, so you'll hit RAM limits without warning. I've crashed my system twice this way.

Update Process: Auto-updates sometimes break existing setups. I've had to reinstall twice after updates fucked up my model configs.

The GitHub repo has 900+ open issues, which tells you something about the stability situation.

Questions People Actually Ask

Q

Why does my Docker container keep crashing when I load large models?

A

Your GPU's out of VRAM and Jan's error messages are fucking useless. Run docker stats to see what's actually happening. Hit the memory ceiling? Use smaller models or suffer through CPU inference. Learned this the hard way after 2 hours of debugging.

Q

How do I fix "Model failed to load" errors?

A

This error is complete bullshit - it could mean anything. Start with these:

  • Not enough RAM/VRAM (most likely culprit)
  • Corrupted download (delete the GGUF file, redownload)
  • Windows Defender quarantined your model file (check virus logs)
  • Fucked up PATH preventing llama.cpp from loading

Pro tip: Check ~/jan/logs/ for actual details. The UI error is worthless.

Q

Does Jan actually work better than just using Ollama?

A

Depends what you want. Ollama is faster for CLI nerds and has better model management. Jan has the GUI and MCP tools, but those break half the time. If you just want to run models locally without fuss, use Ollama. If you want the tool integration experiment, try Jan.

Q

Why is performance so shitty on Windows compared to Mac?

A

Windows builds are clearly an afterthought. The Windows version has issues with:

  • GPU detection and driver compatibility
  • Model loading taking 2x longer
  • Random crashes that don't happen on Mac
  • Antivirus software fucking with everything

Jan runs best on Mac, decent on Linux, and is a pain in the ass on Windows.

Q

Can I actually use this for serious work or is it just a demo?

A

For basic shit like writing emails and simple code snippets - yeah, it works. But anything mission-critical? Stick with GPT-4 or Claude. Jan handles maybe 70% of typical AI tasks but craps out on the complex reasoning that actually matters.

The MCP stuff is impressive but breaks at random moments. I wouldn't bet a deadline on it.

Q

Why does Jan use so much memory even when idle?

A

Jan keeps models loaded in memory even when not actively using them. There's no automatic unloading, so switching between models eats RAM quickly. Manual workaround: restart Jan to free memory.

This is dumb design for a desktop app.

Q

Is the 91.1% SimpleQA accuracy claim bullshit?

A

No, that's actually legit for Jan-v1. But SimpleQA is just factual Q&A like "What's the capital of France?" Don't expect the same performance on complex reasoning or creative tasks.

It's a good benchmark but not representative of overall capability.

Q

How do I stop Jan from auto-updating and breaking my setup?

A

Disable auto-updates in settings immediately after installing. Jan's update process has a history of breaking existing configurations. When a new version comes out, backup your models directory first.

Q

Why can't I connect to the localhost:1337 API server?

A

Common issues:

  • Windows firewall blocking the port
  • Another service already using port 1337
  • Jan not actually running the API server (check settings)
  • Trying to connect before a model is loaded

The API only works when you have a model actively loaded.

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