The most aggressive reply to d4

hey guys i wanted to ask what is the most aggressive reply to d4 which lead to sharp tactical play

The Budapest gambit comes to mind, but IMO any White player who's looked into it before will know how to neutralize its venom (at least, that's my experience at my rating level). Slightly less aggressive but more playable (if you know your lines) would be the Albin countergambit, or the well-respected Tarrasch variation of the QGD.

And, of course, there are the big-name openings like the King's Indian Defense (although you'll have to watch out for the exchange variations if you're bored senseless by them), the Grunfeld, and the Dutch defenses. In the KID and some variations of the Dutch you'll be playing for a menacing kingside pawn storm and king hunt.

@Paracompact Budapest gambit isn't that tactical. Its a bit trappy and not very good. The traps people don't even fall for.

If you want sharp play try Kings Indian or Gruenfeld.

@chessanalyst I agree completely. As a d4 player myself I am much happier to see the Budapest than any of the other openings I mentioned. But if OP just wants to have a fun game or two to try it out at the lower levels, I think it's worth mentioning.

Yeh. Any opening is "playable" at even my level (online 2000ish) no matter how dubious it is (Unless its literally giving away a queen for nothing) and for sure at OP level.

what about the benoni ?

Benoni is not terribly aggressive in and of itself, and is a difficult opening to use well (without accurate play White will just push his center and crush you). Benko gambit is somewhat more aggressive, but you better know what you're sacrificing a pawn for if you're going to play it, because it's not immediately aggressive (you aim for a good endgame, basically).

Semi-Slav is very tactical in nature. If you don't like the exchange slav, you can always play the triangle system (delaying Nf6). You just have to be prepared to meet the Marshall Gambit . d4 d5 2. c4 e6 3. Nc3 c6 4. e4

1. ...d6 leads to tactical fireworks if white castles queen-side or doesn't castle at all. Because then black counter attacks on the queen-side or the center.

But if white castles king-side it will be a positional game.

I love the variations where white and black race to mate, but sadly white can choose to avoid them simply by castling king-side.

I don't exactly know what you mean with an "aggressive" opening...

If you just want an asymmetrical position, with possibilities to play for a win with black, then there's a whole bunch of openings you could try:
The Grünfeld, Nimzo-Indian, Semi-Slav, Benko Gambit, Tarrasch, King's Indian, Benoni and the Dutch Defence all typically lead to imbalanced positions out of the opening. (Unless white plays the Exchange Variations against the Slav or King's Indian Defence...)

If you also want to make sure you get an open position, with tactical themes likely occuring early on, you should probably play the Grünfeld or the Tarrasch. If you also care about the theoretical reputation of the opening you're playing, go for the Grünfeld. ;)