I am using blockcypher send/receive API in certain services and accept Tx with 1+ confirmations. Post SegWit, do I need any change to be made at my end?
No, only if that API did something weird.
Is the API doing "something weird" predictable?
The prediction is it wouldn't.
I mean, if you're using a third party API then at any point they could make you add an argument "moon moon fish moon"... but there is no reason for them to do that; likewise for segwit.
Reading a little about SegWit, what I understood that SegWit addresses will be different from usual addresses. So, how a fund sent to a normal address from a SegWit address will be determined by the API?
p.s. I'm sorry if my Q does not make sense. But, I'm getting a little confused here.As I understand it, there is no as-yet agreed on address format for "pure" segwit (p2wpkh, p2wsh), but segwit can be done in p2sh (see bip 141), so initially a segwit-supporting wallet can receive funds from a non-segwit-supporting wallet using p2sh addresses.
Edit: well, but knightdk's answer still applies if you are talking about APIs. I was just trying to interpret what you were really asking.