Requestor is the older form, derived from the Latin ending -or, which is translated "one who". Hence, a requestor is one who requests. Requester is the English form, following the modern custom of ending such words with -er. Either form is correct.

What does requester mean?

: one who makes a request : one who asks something of another But in Washington state, filing a public records request can put the requester at legal risk of being named in a lawsuit should someone else not want the records to be made public. —

What is the plural of requester?

Noun. requester (plural requesters) One who, or that which, makes a request.