Exact input and exact output

Pass exactly one of amount_in or amount_out. Both are raw integers in the token’s smallest unit (use the token’s decimals from ft_metadata).

Exact input: amount_in

“I pay exactly this much, how much do I get?” This is the most common mode, and every DEX supports it.

amount_in=1000000000000000000000000

Quotes come back with output amounts:

"estimated_amount": { "amount_out": "4880007" },
"worst_case_amount": { "amount_out": "4831206" }

worst_case_amount is the minimum output the transactions accept. If the pools move so that the output would be lower, the swap fails and the input is refunded.

Exact output: amount_out

“I want to receive exactly this much, how much do I pay?”

amount_out=1000000

Quotes come back with input amounts:

"estimated_amount": { "amount_in": "205495745391126196067546" },
"worst_case_amount": { "amount_in": "210222147535122098577099" }

worst_case_amount is the most the trader can pay. The transactions send up to this much and return whatever isn’t used, so the trader needs to hold the worst-case amount, not just the estimate.

Not every DEX supports exact output:

DEX	Exact output
Rhea	❌ No
Rhea DCL	✅ Yes
Plach, Aidols, Wrap, Meta Pool, LiNEAR, rNEAR, xRHEA	✅ Yes

DEXs that don’t support it just don’t return a quote, so you may get fewer quotes than with amount_in.