Look for companies that make software that by has to integrate with existing/competing/legacy software systems. I know that's vague but there are companies tha

Look for companies that make software that by has to integrate with existing/competing/legacy software systems. I know that's vague but there are companies that make new products that for one reason or another need to talk to old products and the source, APIs, even binary interfaces are opaque, undocumented, obfuscated or otherwise unaccessible. Developer tools, CAD/EDA, embedded systems... lots of people are building new stacks that have to talk to older ones at some point.