Router

Because routers are stateless and do not hold token balances, they can be replaced safely and trustlessly, if necessary. This may happen if more efficient smart contract patterns are discovered, or if additional functionality is desired. For this reason, routers have release numbers, starting at 01.

Routers also contain all Library functions.

Code

UniswapV2Router01.sol

Address

UniswapV2Router01 is deployed at 0xcDbE04934d89e97a24BCc07c3562DC8CF17d8167 on the Ropsten, Rinkeby, Görli, and Kovan testnets.

Read-Only Functions

WETH

function WETH() external view returns (address);

Returns the canonical WETH address on the Ethereum mainnet, or the Ropsten, Rinkeby, Görli, or Kovan testnets.

State-Changing Functions

addLiquidity

function addLiquidity(
address tokenA,
address tokenB,
uint amountADesired,
uint amountBDesired,
uint amountAMin,
uint amountBMin,
address to,
uint deadline
) external returns (uint amountA, uint amountB, uint liquidity);

Adds liquidity to an ERC-20⇄ERC-20 pool.

  • To cover all possible scenarios, msg.sender should have already given the router an allowance of at least amountADesired/amountBDesired on tokenA/tokenB.
  • Always adds assets at the ideal ratio, according to the price when the transaction is executed.
  • If a pool for the passed tokens does not exists, one is created automatically, and exactly amountADesired/amountBDesired tokens are added.
NameType
tokenAaddressA pool token.
tokenBaddressA pool token.
amountADesireduintThe amount of tokenA to add as liquidity if the B/A price is <= amountBDesired/amountADesired (A depreciates).
amountBDesireduintThe amount of tokenB to add as liquidity if the A/B price is <= amountADesired/amountBDesired (B depreciates).
amountAMinuintBounds the extent to which the B/A price can go up before the transaction reverts. Must be <= amountADesired.
amountBMinuintBounds the extent to which the A/B price can go up before the transaction reverts. Must be <= amountBDesired.
toaddressRecipient of the liquidity tokens.
deadlineuintUnix timestamp after which the transaction will revert.
amountAuintThe amount of tokenA sent to the pool.
amountBuintThe amount of tokenB sent to the pool.
liquidityuintThe amount of liquidity tokens minted.

addLiquidityETH

function addLiquidityETH(
address token,
uint amountTokenDesired,
uint amountTokenMin,
uint amountETHMin,
address to,
uint deadline
) external payable returns (uint amountToken, uint amountETH, uint liquidity);

Adds liquidity to an ERC-20⇄WETH pool with ETH.

  • To cover all possible scenarios, msg.sender should have already given the router an allowance of at least amountTokenDesired on token.
  • Always adds assets at the ideal ratio, according to the price when the transaction is executed.
  • msg.value is treated as a amountETHDesired.
  • Leftover ETH, if any, is returned to msg.sender.
  • If a pool for the passed token and WETH does not exists, one is created automatically, and exactly amountTokenDesired/msg.value tokens are added.
NameType
tokenaddressA pool token.
amountTokenDesireduintThe amount of token to add as liquidity if the WETH/token price is <= msg.value/amountTokenDesired (token depreciates).
msg.value (amountETHDesired)uintThe amount of ETH to add as liquidity if the token/WETH price is <= amountTokenDesired/msg.value (WETH depreciates).
amountTokenMinuintBounds the extent to which the WETH/token price can go up before the transaction reverts. Must be <= amountTokenDesired.
amountETHMinuintBounds the extent to which the token/WETH price can go up before the transaction reverts. Must be <= msg.value.
toaddressRecipient of the liquidity tokens.
deadlineuintUnix timestamp after which the transaction will revert.
amountTokenuintThe amount of token sent to the pool.
amountETHuintThe amount of ETH converted to WETH and sent to the pool.
liquidityuintThe amount of liquidity tokens minted.

removeLiquidity

function removeLiquidity(
address tokenA,
address tokenB,
uint liquidity,
uint amountAMin,
uint amountBMin,
address to,
uint deadline
) external returns (uint amountA, uint amountB);

Removes liquidity from an ERC-20⇄ERC-20 pool.

  • msg.sender should have already given the router an allowance of at least liquidity on the pool.
NameType
tokenAaddressA pool token.
tokenBaddressA pool token.
liquidityuintThe amount of liquidity tokens to remove.
amountAMinuintThe minimum amount of tokenA that must be received for the transaction not to revert.
amountBMinuintThe minimum amount of tokenB that must be received for the transaction not to revert.
toaddressRecipient of the underlying assets.
deadlineuintUnix timestamp after which the transaction will revert.
amountAuintThe amount of tokenA received.
amountBuintThe amount of tokenB received.

removeLiquidityETH

function removeLiquidityETH(
address token,
uint liquidity,
uint amountTokenMin,
uint amountETHMin,
address to,
uint deadline
) external returns (uint amountToken, uint amountETH);

Removes liquidity from an ERC-20⇄WETH pool and receive ETH.

  • msg.sender should have already given the router an allowance of at least liquidity on the pool.
NameType
tokenaddressA pool token.
liquidityuintThe amount of liquidity tokens to remove.
amountTokenMinuintThe minimum amount of token that must be received for the transaction not to revert.
amountETHMinuintThe minimum amount of ETH that must be received for the transaction not to revert.
toaddressRecipient of the underlying assets.
deadlineuintUnix timestamp after which the transaction will revert.
amountTokenuintThe amount of token received.
amountETHuintThe amount of ETH received.

removeLiquidityWithPermit

function removeLiquidityWithPermit(
address tokenA,
address tokenB,
uint liquidity,
uint amountAMin,
uint amountBMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external returns (uint amountA, uint amountB);

Removes liquidity from an ERC-20⇄ERC-20 pool without pre-approval, thanks to permit.

NameType
tokenAaddressA pool token.
tokenBaddressA pool token.
liquidityuintThe amount of liquidity tokens to remove.
amountAMinuintThe minimum amount of tokenA that must be received for the transaction not to revert.
amountBMinuintThe minimum amount of tokenB that must be received for the transaction not to revert.
toaddressRecipient of the underlying assets.
deadlineuintUnix timestamp after which the transaction will revert.
approveMaxboolWhether or not the approval amount in the signature is for liquidity or uint(-1).
vuint8The v component of the permit signature.
rbytes32The r component of the permit signature.
sbytes32The s component of the permit signature.
amountAuintThe amount of tokenA received.
amountBuintThe amount of tokenB received.

removeLiquidityETHWithPermit

function removeLiquidityETHWithPermit(
address token,
uint liquidity,
uint amountTokenMin,
uint amountETHMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external returns (uint amountToken, uint amountETH);

Removes liquidity from an ERC-20⇄WETTH pool and receive ETH without pre-approval, thanks to permit.

NameType
tokenaddressA pool token.
liquidityuintThe amount of liquidity tokens to remove.
amountTokenMinuintThe minimum amount of token that must be received for the transaction not to revert.
amountETHMinuintThe minimum amount of ETH that must be received for the transaction not to revert.
toaddressRecipient of the underlying assets.
deadlineuintUnix timestamp after which the transaction will revert.
approveMaxboolWhether or not the approval amount in the signature is for liquidity or uint(-1).
vuint8The v component of the permit signature.
rbytes32The r component of the permit signature.
sbytes32The s component of the permit signature.
amountTokenuintThe amount of token received.
amountETHuintThe amount of ETH received.

swapExactTokensForTokens

function swapExactTokensForTokens(
uint amountIn,
uint amountOutMin,
address[] calldata path,
address to,
uint deadline
) external returns (uint[] memory amounts);

Swaps an exact amount of input tokens for as many output tokens as possible, along the route determined by the path. The first element of path is the input token, the last is the output token, and any intermediate elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).

  • msg.sender should have already given the router an allowance of at least amountIn on the input token.
NameType
amountInuintThe amount of input tokens to send.
amountOutMinuintThe minimum amount of output tokens that must be received for the transaction not to revert.
pathaddress[] calldataAn array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses must exist and have liquidity.
toaddressRecipient of the output tokens.
deadlineuintUnix timestamp after which the transaction will revert.
amountsuint[] memoryThe input token amount and all subsequent output token amounts.

swapTokensForExactTokens

function swapTokensForExactTokens(
uint amountOut,
uint amountInMax,
address[] calldata path,
address to,
uint deadline
) external returns (uint[] memory amounts);

Receive an exact amount of output tokens for as few input tokens as possible, along the route determined by the path. The first element of path is the input token, the last is the output token, and any intermediate elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).

  • msg.sender should have already given the router an allowance of at least amountInMax on the input token.
NameType
amountOutuintThe amount of output tokens to receive.
amountInMaxuintThe maximum amount of input tokens that can be required before the transaction reverts.
pathaddress[] calldataAn array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses must exist and have liquidity.
toaddressRecipient of the output tokens.
deadlineuintUnix timestamp after which the transaction will revert.
amountsuint[] memoryThe input token amount and all subsequent output token amounts.

swapExactETHForTokens

function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
external
payable
returns (uint[] memory amounts);

Swaps an exact amount of ETH for as many output tokens as possible, along the route determined by the path. The first element of path must be WETH, the last is the output token, and any intermediate elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).

NameType
msg.value (amountIn)uintThe amount of ETH to send.
amountOutMinuintThe minimum amount of output tokens that must be received for the transaction not to revert.
pathaddress[] calldataAn array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses must exist and have liquidity.
toaddressRecipient of the output tokens.
deadlineuintUnix timestamp after which the transaction will revert.
amountsuint[] memoryThe input token amount and all subsequent output token amounts.

swapTokensForExactETH

function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
external
returns (uint[] memory amounts);

Receive an exact amount of ETH for as few input tokens as possible, along the route determined by the path. The first element of path is the input token, the last must be WETH, and any intermediate elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).

  • msg.sender should have already given the router an allowance of at least amountInMax on the input token.
NameType
amountOutuintThe amount of ETH to receive.
amountInMaxuintThe maximum amount of input tokens that can be required before the transaction reverts.
pathaddress[] calldataAn array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses must exist and have liquidity.
toaddressRecipient of ETH.
deadlineuintUnix timestamp after which the transaction will revert.
amountsuint[] memoryThe input token amount and all subsequent output token amounts.

swapExactTokensForETH

function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
external
returns (uint[] memory amounts);

Swaps an exact amount of tokens for as much ETH as possible, along the route determined by the path. The first element of path is the input token, the last must be WETH, and any intermediate elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).

NameType
amountInuintThe amount of input tokens to send.
amountOutMinuintThe minimum amount of output tokens that must be received for the transaction not to revert.
pathaddress[] calldataAn array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses must exist and have liquidity.
toaddressRecipient of the ETH.
deadlineuintUnix timestamp after which the transaction will revert.
amountsuint[] memoryThe input token amount and all subsequent output token amounts.

swapETHForExactTokens

function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
external
payable
returns (uint[] memory amounts);

Receive an exact amount of tokens for as little ETH as possible, along the route determined by the path. The first element of path must be WETH, the last is the output token and any intermediate elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).

  • Leftover ETH, if any, is returned to msg.sender.
NameType
amountOutuintThe amount of tokens to receive.
msg.value (amountInMax)uintThe maximum amount of ETH that can be required before the transaction reverts.
pathaddress[] calldataAn array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses must exist and have liquidity.
toaddressRecipient of the output tokens.
deadlineuintUnix timestamp after which the transaction will revert.
amountsuint[] memoryThe input token amount and all subsequent output token amounts.

Interface

interface IUniswapV2Router01 {
function WETH() external view returns (address);

function addLiquidity(
address tokenA,
address tokenB,
uint amountADesired,
uint amountBDesired,
uint amountAMin,
uint amountBMin,
address to,
uint deadline
) external returns (uint amountA, uint amountB, uint liquidity);
function addLiquidityETH(
address token,
uint amountTokenDesired,
uint amountTokenMin,
uint amountETHMin,
address to,
uint deadline
) external payable returns (uint amountToken, uint amountETH, uint liquidity);
function removeLiquidity(
address tokenA,
address tokenB,
uint liquidity,
uint amountAMin,
uint amountBMin,
address to,
uint deadline
) external returns (uint amountA, uint amountB);
function removeLiquidityETH(
address token,
uint liquidity,
uint amountTokenMin,
uint amountETHMin,
address to,
uint deadline
) external returns (uint amountToken, uint amountETH);
function removeLiquidityWithPermit(
address tokenA,
address tokenB,
uint liquidity,
uint amountAMin,
uint amountBMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external returns (uint amountA, uint amountB);
function removeLiquidityETHWithPermit(
address token,
uint liquidity,
uint amountTokenMin,
uint amountETHMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external returns (uint amountToken, uint amountETH);
function swapExactTokensForTokens(
uint amountIn,
uint amountOutMin,
address[] calldata path,
address to,
uint deadline
) external returns (uint[] memory amounts);
function swapTokensForExactTokens(
uint amountOut,
uint amountInMax,
address[] calldata path,
address to,
uint deadline
) external returns (uint[] memory amounts);
function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
external
payable
returns (uint[] memory amounts);
function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
external
returns (uint[] memory amounts);
function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
external
returns (uint[] memory amounts);
function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
external
payable
returns (uint[] memory amounts);
}

ABI

[
{
"constant": true,
"inputs": [],
"name": "WETH",
"outputs": [{ "internalType": "address", "name": "", "type": "address" }],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "address", "name": "tokenA", "type": "address" },
{ "internalType": "address", "name": "tokenB", "type": "address" },
{ "internalType": "uint256", "name": "amountADesired", "type": "uint256" },
{ "internalType": "uint256", "name": "amountBDesired", "type": "uint256" },
{ "internalType": "uint256", "name": "amountAMin", "type": "uint256" },
{ "internalType": "uint256", "name": "amountBMin", "type": "uint256" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "addLiquidity",
"outputs": [
{ "internalType": "uint256", "name": "amountA", "type": "uint256" },
{ "internalType": "uint256", "name": "amountB", "type": "uint256" },
{ "internalType": "uint256", "name": "liquidity", "type": "uint256" }
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "address", "name": "token", "type": "address" },
{ "internalType": "uint256", "name": "amountTokenDesired", "type": "uint256" },
{ "internalType": "uint256", "name": "amountTokenMin", "type": "uint256" },
{ "internalType": "uint256", "name": "amountETHMin", "type": "uint256" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "addLiquidityETH",
"outputs": [
{ "internalType": "uint256", "name": "amountToken", "type": "uint256" },
{ "internalType": "uint256", "name": "amountETH", "type": "uint256" },
{ "internalType": "uint256", "name": "liquidity", "type": "uint256" }
],
"payable": true,
"stateMutability": "payable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "address", "name": "tokenA", "type": "address" },
{ "internalType": "address", "name": "tokenB", "type": "address" },
{ "internalType": "uint256", "name": "liquidity", "type": "uint256" },
{ "internalType": "uint256", "name": "amountAMin", "type": "uint256" },
{ "internalType": "uint256", "name": "amountBMin", "type": "uint256" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "removeLiquidity",
"outputs": [
{ "internalType": "uint256", "name": "amountA", "type": "uint256" },
{ "internalType": "uint256", "name": "amountB", "type": "uint256" }
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "address", "name": "token", "type": "address" },
{ "internalType": "uint256", "name": "liquidity", "type": "uint256" },
{ "internalType": "uint256", "name": "amountTokenMin", "type": "uint256" },
{ "internalType": "uint256", "name": "amountETHMin", "type": "uint256" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "removeLiquidityETH",
"outputs": [
{ "internalType": "uint256", "name": "amountToken", "type": "uint256" },
{ "internalType": "uint256", "name": "amountETH", "type": "uint256" }
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "address", "name": "token", "type": "address" },
{ "internalType": "uint256", "name": "liquidity", "type": "uint256" },
{ "internalType": "uint256", "name": "amountTokenMin", "type": "uint256" },
{ "internalType": "uint256", "name": "amountETHMin", "type": "uint256" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" },
{ "internalType": "bool", "name": "approveMax", "type": "bool" },
{ "internalType": "uint8", "name": "v", "type": "uint8" },
{ "internalType": "bytes32", "name": "r", "type": "bytes32" },
{ "internalType": "bytes32", "name": "s", "type": "bytes32" }
],
"name": "removeLiquidityETHWithPermit",
"outputs": [
{ "internalType": "uint256", "name": "amountToken", "type": "uint256" },
{ "internalType": "uint256", "name": "amountETH", "type": "uint256" }
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "address", "name": "tokenA", "type": "address" },
{ "internalType": "address", "name": "tokenB", "type": "address" },
{ "internalType": "uint256", "name": "liquidity", "type": "uint256" },
{ "internalType": "uint256", "name": "amountAMin", "type": "uint256" },
{ "internalType": "uint256", "name": "amountBMin", "type": "uint256" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" },
{ "internalType": "bool", "name": "approveMax", "type": "bool" },
{ "internalType": "uint8", "name": "v", "type": "uint8" },
{ "internalType": "bytes32", "name": "r", "type": "bytes32" },
{ "internalType": "bytes32", "name": "s", "type": "bytes32" }
],
"name": "removeLiquidityWithPermit",
"outputs": [
{ "internalType": "uint256", "name": "amountA", "type": "uint256" },
{ "internalType": "uint256", "name": "amountB", "type": "uint256" }
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "uint256", "name": "amountOut", "type": "uint256" },
{ "internalType": "address[]", "name": "path", "type": "address[]" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "swapETHForExactTokens",
"outputs": [{ "internalType": "uint256[]", "name": "amounts", "type": "uint256[]" }],
"payable": true,
"stateMutability": "payable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "uint256", "name": "amountOutMin", "type": "uint256" },
{ "internalType": "address[]", "name": "path", "type": "address[]" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "swapExactETHForTokens",
"outputs": [{ "internalType": "uint256[]", "name": "amounts", "type": "uint256[]" }],
"payable": true,
"stateMutability": "payable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "uint256", "name": "amountIn", "type": "uint256" },
{ "internalType": "uint256", "name": "amountOutMin", "type": "uint256" },
{ "internalType": "address[]", "name": "path", "type": "address[]" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "swapExactTokensForETH",
"outputs": [{ "internalType": "uint256[]", "name": "amounts", "type": "uint256[]" }],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "uint256", "name": "amountIn", "type": "uint256" },
{ "internalType": "uint256", "name": "amountOutMin", "type": "uint256" },
{ "internalType": "address[]", "name": "path", "type": "address[]" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "swapExactTokensForTokens",
"outputs": [{ "internalType": "uint256[]", "name": "amounts", "type": "uint256[]" }],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "uint256", "name": "amountOut", "type": "uint256" },
{ "internalType": "uint256", "name": "amountInMax", "type": "uint256" },
{ "internalType": "address[]", "name": "path", "type": "address[]" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "swapTokensForExactETH",
"outputs": [{ "internalType": "uint256[]", "name": "amounts", "type": "uint256[]" }],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{ "internalType": "uint256", "name": "amountOut", "type": "uint256" },
{ "internalType": "uint256", "name": "amountInMax", "type": "uint256" },
{ "internalType": "address[]", "name": "path", "type": "address[]" },
{ "internalType": "address", "name": "to", "type": "address" },
{ "internalType": "uint256", "name": "deadline", "type": "uint256" }
],
"name": "swapTokensForExactTokens",
"outputs": [{ "internalType": "uint256[]", "name": "amounts", "type": "uint256[]" }],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
}
]

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