Barcelona-based 3Scale Networks is launching its API management service today at the Plugg conference (which is run by TechCrunch editor Robin Wauters). With every Web startup releasing their own APIs as a matter of course these days, 3Scale offers a startups who don’t want to deal with all the hassles of managing their own APIs their own enterprise Web service that does it for them.

3Scale manages signups, tracks usage, offers user forums, stores online documentation, and handles online billing. The service runs on Amazon’s EC2, S3 ,and cloud computing Web services. 3Scale starts charging only once the billing for an API kicks in, which is usually above a certain threshold of free usage. 3Scale was previously in beta. Now companies can host their API management portal on their own sub-domain.

The startup will be competing with Mashery, which has been helping other companies manage their APIs for quite a while now. 3Scale co-founder Steven Willmott says that he is taking a more light-weight, self-serve approach, which he hopes will broaden the appeal of API management services.