How to Set Up Cat and Mouse With OBS in Under 5 Minutes

Before You Start

Cat and Mouse connects to OBS through its WebSocket server. That means OBS needs to have WebSocket enabled before the app can talk to it. If you've never touched that setting, don't worry, it takes about thirty seconds.

You'll need OBS Studio (or Streamlabs OBS), a webcam already added as a source in your scene, and the Cat and Mouse app installed from catnmouse.app. The app is Windows only right now, so if you're on Mac, you'll need to wait for that release.

Step 1: Enable WebSocket in OBS

Open OBS and go to Tools in the top menu bar. Click on WebSocket Server Settings. Check the box that says Enable WebSocket Server. You'll see a port number, usually 4455 by default, and an option to set a password. Write down the port and password if you set one. Hit OK.

That's it for OBS setup. You don't need to change anything else.

Step 2: Make Sure Your Webcam Source Is in Your Scene

Cat and Mouse detects your webcam source automatically, but it needs to be in the active scene. If your webcam is on a different scene or not visible, the app won't have anything to move.

Just confirm you can see your webcam overlay in your current scene before launching Cat and Mouse.

Step 3: Connect Cat and Mouse to OBS

Open Cat and Mouse. On the connection screen, enter the WebSocket port from earlier (4455 if you left it as default) and your password if you set one. Hit Connect.

If everything is right, the app will connect to OBS and show you that it's found your webcam source. At this point, dodging is already active. Move your mouse toward your webcam overlay and watch it move away.

Step 4: Adjust the Dodge Sensitivity

By default, the webcam starts moving when your cursor gets within a certain distance. You can tune this in the app settings. If the webcam feels jumpy or moves too early, pull the sensitivity down. If it's not moving until you're basically on top of it, push it up.

Spend two minutes with this during a test stream before going live. You want it to feel natural, not distracting.

Step 5: Style Your Webcam While You're There

This part is optional but worth doing once. Cat and Mouse has a live styling panel that lets you change your webcam shape, add a border, or dial in a glow effect without touching OBS filters.

Click the shape you want: circle, rounded rectangle, or portrait. Pick a border color using the color picker. Drag the glow intensity slider if you want a soft light around your webcam. Every change applies live in OBS as you make it, so you can see exactly what your viewers will see.

This alone saves a lot of time if you've ever tried to set up a circular webcam mask in OBS manually. That process involves finding a PNG mask file, adding an image mask filter, adjusting crop, hoping the aspect ratio is right. Cat and Mouse replaces all of that with a single click.

Running It During Your Stream

Cat and Mouse runs in the background while you stream. You don't need to keep its window open. Once it's connected and configured, you can minimize it and forget it's there.

If you want to change your webcam style mid-stream, just bring the window back up. Changes apply in real time, so there's no interruption.

One Thing to Note

Make sure Cat and Mouse is running before you go live. It connects to OBS at startup, so if OBS isn't open yet when you launch the app, just hit Reconnect once OBS is ready. The whole setup becomes muscle memory after the first couple of streams.