If it it for USA, widely accepted one is with WES.org. But the problem is WES.org is, they require certified copy by TU examination board sent directly by TU (considering your certificate is from TU). I know its stupid to ask TU to send certified copy to USA. TU will never do it and WES.org never understands that. What I have seen people doing is, get certified copy from TU examination controller, keep certified document in a TU sealed envelope and post to WES.org. And I know this works.... however, TU requires original certificate for certification.

I hope this helps.