Throttle network speeds for a specific host in Charles

Sometimes you'll want to test whether your app works properly under poor networking conditions. One way to test this is Apple's Network Link Conditioner. Unfortunately, this will slow internet speeds for your entire machine to a crawl which can be counterproductive. Especially if you want to throttle your app for a longer period of time.

If you have Charles installed to debug your app's network traffic, you can use it to throttle network speeds for the entire system, or for a selection of hosts which is exactly what we're looking for.

To enable throttling in Charles you can either go to Proxy -> Start Throttling or press cmd + T. This will turn on global throttling by default.

You can configure how Charles throttles, and for which hosts through Proxy -> Throttle Settings or by pressing cmd + shift + T. Make sure to check the Only for selected hosts checkbox if you want to configure which hosts should be throttled.

Click the Add button to add a new host that should be throttled.

Use the bottom section of the Throttle Settings to configure how the network connection should be throttled. This configuration is applied to all throttled hosts.