I've just written a tool for iOS using the ‘Workflow’ app engine (crude interpreted language): it is a callable function to convert a MAC-48 address into the corresponding IPv6 64-bit interface identifier. I've also put together a program that is based on this routine which either converts clipboard contents, or takes input from another program and pushes the result to the clipboard. It can optionally validate the input too.
It takes MAC addresses in any of the three syntactic formats, it doesn't care.
I've just thought: I ought to write another tool to do conversions into the different syntactic formats for MAC addresses.
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I just found a web-based tool :
http://ben.akrin.com/?p=1347And it has an http-based API as well.