How to specify wildcards in proxy exceptions in Firefox?

You can define wildcards with the CIDR notation. For example:

10.0.0.0/8

specifies the range from 10.0.0.0 up to 10.255.255.255

See for more information: CIDR

I think you can just add the domain e.g.

.mydomain.org

Will pick up any variant. I don't know about mycompany-*

I believe it also supports ranges e.g. 192.168.1.0/8

I was faced with a similar problem (however it was only for local machines on our network)

I needed to bypass the proxy for all our local machines. These start in the format abcXXX where XXX is a value from 000 - 999

For example one development server may be hosted on abc303 and the other on abc909.

We tried the CIDR method in our proxy execptions as all machines had an IP address in the 10.0.0.0/8 however, we still faced issues.

We manged to fix this by adding

<local> 

to our proxy exceptions

I couldn't find a lot of information on this but it is mentioned in Mozilla's Bug 72444 - Proxy: "bypass proxy server for local addresses" bug request.