It's not Tony as that letter was surprise for him , that means Cap is contacting him by letter first time after the fight.

@AnkitSharma Who says that Tony hadn't already decided to leak that information to Cap before he received the letter though?

Then we can speculated anything, even Sharon Carter or maybe the security guy or maybe ..............

@AnkitSharma Yes, we can; but these are the most likely options, which is why I posted them. And as I say in the answer itself; "I doubt we will ever have a direct confirmation about how Steve found The Raft as ultimately, it doesn't matter. What matters is that he did find it."

@DrRDizzle But to me Sharon Carter made more sense then Tony

@AnkitSharma Sharon Carter had nothing to do with the Accords or the people that signed them. Her involvement in the story is minimal.

@DrRDizzle She stole there gadgets and costume. She knows stuff. Doesn't it depends on who can do it rather then there screen time in film?

@AnkitSharma That's true, but by that logic literally any character in the film or Agents of SHIELD or the Netflix shows could be the one who told Steve where The Raft is. I'm just listing what I believe to be the most likely explanations, and I don't think Sharon Carter is one.

@DrRDizzle Tony who literally tried to kill him is better contender then his own gf (Sharon Carter). She helped him in the film Civil War not some maybe-canon TV show. And if Sharon Carter can know where there gadgets and costume are and even easily steal them, then they why can't she know the place for Raft and told that to cap?

@AnkitSharma Tony didn't try to kill Steve, he tried to kill Bucky. And there is a big difference between Sharon knowing where Cap's SHIELD will be stored (she's the one who takes it into storage after all; we see her give Steve and Sam the receipts for their items) and knowing where a top secret facility for imprisoning super villains is located. Bear in mind that no-one on Team Cap even knew that the Raft existed before they were imprisoned there.

so?

No one even knows where there costume and gadgets were

But she does

@DrRDizzle Natasha was also on there list way before other get imprisoned because she ditched them, so why would they tell her raft location. And if she can know , so does agent 13 can

@AnkitSharma That's my whole point. It's established that Sharon knows where the SHIELD and EXO-7 are, because she put them there. It's never established that she knows where The Raft is, but it is established that Tony and T'Challa know where The Raft is. Which means it's more likely that they told Steve than Sharon did.

Tony not going to help him

@AnkitSharma She was a vital part of the creation of the Accords though; she was at the signing and she supported them from day one. It's more likely that she already knew before she swapped sides; and even if she didn't, she's literally the best spy who has ever existed. She could (probably) find out.

And when is it established T'Challa knows the location?

@AnkitSharma He tracks Iron Man from The Raft one the way to Siberia at the end of the film. He was clearly already in the area.

@DrRDizzle best spy, quite a big term as we don't know about all the spies in MCU

That's how T'Challa ends up with Bucky, Steve, Tony and Zemo at the end.

@DrRDizzle That was different location not raft

@AnkitSharma Yes, but T'Challa follows Tony there from The Raft.

I am dam sure Tony is not going to help at all and his fight clearly shown that he didn't mind killing cap either if its required to reach to bucky

He was not fighting with pillows

@AnkitSharma No, but he also wasn't trying to kill Steve. He's constantly giving him warnings to "stay down" etc.

But more importantly, we see that Tony realises he was wrong when he talks to Sam Wilson at The Raft. And we also see that Tony is happy to receive a letter from Steve; despite their fight, the two of them clearly still want to be friends, even if that's going to be very difficult now.

He was shooting blast , i don't know if his blast are programmed not to kill cap if he comes in coverage area.

I can see that Tony (who has always suffered from his guilt about various things) might try to ease that guilt by leaking info about The Raft in order to free Sam, Scott, Wanda etc.

@DrRDizzle you are mixing stuff, the moment when he decided to kill bucky happened after raft and before letter scene

@DrRDizzle he never gave shit to Wanada.

Steve might have signed it before he mentioned what going to happen with wnada after that incident

@AnkitSharma I know the order events happened in. He visits the Raft, sees that his friends are imprisoned and quite obviously isn't happy about it, deceiving General Ross and leaving before heading to Siberia in secret. Then he tries to kill Bucky, and then some time later he receives the letter. There is a whole lot of time between those last two events in which Tony could have seen that he was acting irrationally, and that to make amends he's going to help free his friends from The Raft

Hell, even while Tony is reading the letter from Steve, we can see he's not angry or frustrated. He's just mildly sad.

He was never seen guilty after fight with bucky till he read that letter

@AnkitSharma You're wrong. When he's talking to Sam, he admits that he wrong about the Accords, disables the sound on the cameras in The Raft and asks for Sams help. Then, when he learns that the Raft is under attack (when General Ross phones him at the end), he puts Ross on hold.

He's clearly OK with Steve breaking them out. I posit that he may have gone one step further and had an active role in it.

@DrRDizzle again you missed the whole point

He clearly tired to kill a innocent human in the next scene

@DrRDizzle It was never established at all, he never shown any concern to wanada in film at all or to any other cap's avengers

......

Reminder to the outsiders, join-at-ur-own-risk ;D

@AnkitSharma Because he found out that person killed his mom. He's acting on pure emotion on that point, not sound logical reasoning. Given time to cool down and rationalise the situation, he does.

I'm not saying Tony definitely leaked the information. I'm saying it's one of the possibilities.

And my point is , he the least expected contender then agent 13 and other 2 you mentioned

He's still more likely than Sharon Carter, who has no knowledge of The Raft that we see!

We didn't see that she didn't know, she is from SHIELD .

@AnkitSharma It wasn't a SHIELD operation.

And even if it was, she doesn't work for SHIELD now. She works for the CIA.

She was involved in hiding Superhero costume and knows about where they keep bucky but not about raft.

@AnkitSharma Maybe. That's my whole point; we don't know what she knows.

But we do know what Tony knows.

And T'Challa.

But if we want to speculate then, to me she can be a contender, as she had loyalty towards cap more then tony