REST API and Authtokens limit

REST API and Authtokens limit

I just want to know that is there any limitation on Rest API (for Zoho Creator) using external scripts like PHP Curl etc...

AND

Is Authtokens are limited? what i mean, that Authtokens usage is unlimited or there is a certain limit for using authtokens, like 50/100/200 (any count) times per minute/hour/day etc.....

kindly assist me and sorry for my poor justification.