Is 'to' needed after send in sentences? Please see the below example
Please send to me your details.
or
Please send me your details.
What kind of words don't need to use 'to'?
Ashru
You are asking which verbs require the use of "to" for the indirect object.
As a first step, you can note that the short Anglo-Saxon words often don't:
give me, tell me, send, show, ask, answer, forward ...
Words with similar meaning, but derived from French/Latin, often need "to":
donate to me, relate to me, demonstrate, request (of, from), explain ...
Naturally, there are exceptions.
You can say, "Sing me a song", but not "Sing me".