A jew deposited more money in my account that he was supposed.
I noticed him through via w app.
He saw the message but did not claim the money.
Should I discover his account and deposit the money or once I noticed him and he saw the message I have no Chiyuv till he notifies me?
There are different opinions about this, but numerous poskim say that once you notified him and you know that indeed he did get the message and he indeed knows about it, you are not obligated to bring the money to him ( and in your case to deposit it into his account), although that would be a considerate thing to do. (As a side point, this is really a chesed that you would want others to do for you.) On the other hand, you are not obligated to bring it to him. In fact there is an opinion that you can inform the owner that if he doesn’t come to claim his money until a reasonable amount of time, that you may be mafkir the money.
Mishpitei Hoaveida siman 159-14, that this is the opinion of the Chazon Ish, R’ Moshe Feinstein and R’ Eliyashiv zt”l. Hashovas Aveida Khilchoso 3-6 in the name of R’ N. Karetiz shlit”a.