Look for ELE diplomas.  (Teaching Spanish as a foreign language - Español como lengua extranjera)

Do you mean for italki? As far as being a tutor on italki, you don't need certification. As far as being a teacher, I'm not 100% sure because I'm not one but a teacher had once told me that italki accepts any certificate that is referencing the language you want to teach. So, maybe look up what teaching certificates there are in Spanish and find someplace online that offers that. 

<ul class="list-inline text-light-gray no-margin-b"><li><a ui-sref="user({id:comment.commenter_obj.id})" href="https://www.italki.com/user/5326890">Chris</a>,</li></ul>

Thank you very much!

<ul class="list-inline text-light-gray no-margin-b"><li><a ui-sref="user({id:comment.commenter_obj.id})" href="https://www.italki.com/user/4180934" style="color: rgb(149, 149, 149); outline: 0px;">Casey</a>,</li></ul>

No, I'm not talking about becoming an italki teacher/tutor. I know the requirements, though.