I've written some clever software. It takes a piece of text as an input - a few words, a sentence or a paragraph, even a full page - and it tells you what language the text is written in. It can distinguish between German, Swedish, English, and a dozen or so others, with better than 95 % accuracy.

This was outside of work, and doesn't violate any copyright, non-compete, or other laws and agreements. I know it's commercially useful, but I'm not sure all of the different ways, or how to get in touch with / noticed by the people who could make good use of it.

Google already does something like this; my English searches return English pages. Plenty of other companies spider the web, and then do something with the pages they find ... if this is done automatically, the spiders just record what they find, without knowing or caring whether it's the right language. I don't know which companies ... but I'm guessing most of them could benefit from filtering out the data they don't need.

How do I go about marketing this software?

Did you want to make this sort of program open-source? Or are you looking to make a profit from it?

I can only see this being used in a way that would help other companies make a profit; I just don't see much use for it on a personal level. So I'd be hoping to make a cut...

I could see it being used by recruiters in the EU. Or as part of a front-end to translation software (auto-magically picking the 'from' language).