I live in Germany, so it might differ from your country. Usually I use nearby search with "software" or "IT" for a few different locations and strategies:

- My home address (here I look in a broader radius to not miss anything) - Areas with high IT company concentration (often I already see this high concentrated areas in the nearby home search) - Areas near tech universities (where the experts are)

This should give you a brief overview but unfortunately this list is pretty unqualified. After this I tend to visit the homepages to get an impression of the company.

It's a lot of work but mostly, you have to do this once and only give the list a refresh after a few years.