Can I register a new file extension?

Application developers (people who write the applications we use and who are producing new ones all the time) sometimes need to come up with new types of file. The question that is sometimes asked is whether there is a single central registrar of file extensions, and whether it is possible to register a file extension to an application.

There is no central registrar of file extensions. If there were then it would be likely that each file extension would map to only a single file type and we would not have the confusion that sometimes arises from two or more applications using the same file extension. For better or for worse, each application developer is quite free to choose whatever file extension they want to use for their application.

Whilst there is no central registrar of file extensions, you can use this site to look up whether a given file extension has already been used and you can submit a file extension to this website for your application. Indeed, we would encourage you to submit any new file extensions. This helps to make other people aware of the new file extension and of your application.

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