WETH and the WETH9 Contract

WETH (Wrapped Ether)

WETH is ETH deposited into the WETH9 contract and reissued 1:1 as an ERC-20 token. It exists because ETH predates the ERC-20 standard and cannot be moved by contracts built for tokens. What WETH is.

WETH9

WETH9 is the smart contract that issues WETH: it holds one ETH for every WETH in circulation. On Ethereum mainnet it has been at 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 since December 2017; every major network has its own WETH contract. Contract addresses.

ERC-20

ERC-20 is the Ethereum token standard that defines transfer(), approve() and transferFrom(), so any contract can move any compliant token the same way. WETH implements it; native ETH does not. Wrapped tokens.

Native ETH

Native ETH is the network’s own currency, the one that pays gas. It is not a token contract, which is why DeFi contracts ask for WETH instead. ETH vs WETH.

Peg (1:1)

The peg is the fixed rate between WETH and ETH: 1 WETH can always be redeemed for 1 ETH at the WETH9 contract. Arbitrage keeps market prices on DEXs at that rate. WETH price.

Actions

Wrap

To wrap is to send ETH to the WETH9 contract and receive the same amount of WETH on the same address. It costs one network fee and has no price or slippage. ETH to WETH.

Unwrap

To unwrap is to return WETH to the WETH9 contract and get the same amount of ETH back. Like wrapping, it costs one network fee and nothing else. WETH to ETH.

deposit()

deposit() is the WETH9 function that wraps: it takes the ETH attached to the call and mints the same amount of WETH to the caller. It needs no approval.

withdraw()

withdraw() is the WETH9 function that unwraps: it burns the given amount of WETH from the caller and sends the same amount of ETH back.

Approval (allowance)

An approval is a permission you sign that lets a contract move a set amount of your ERC-20 tokens, such as WETH. Wrapping and unwrapping need none; swaps, lending and NFT bids do. WETH approvals.

Swap

A swap trades one token for another through a DEX liquidity pool, at the pool’s price and with its fee. Swapping USDC for WETH is a trade; ETH to WETH on a DEX screen is usually routed to deposit() instead. How to buy WETH.

Networks and Addresses

Mainnet

Mainnet is the Ethereum main network, where WETH9 was deployed and where network fees are highest. Layer 2 networks settle to it.

Layer 2 (L2)

A layer 2 is a network that executes transactions off Ethereum mainnet and settles them on it, such as Base, Arbitrum and Optimism. Wrapping there costs less than a cent. WETH on Base, WETH on Arbitrum.

Canonical WETH

Canonical WETH is the wrapper a network deploys itself as its standard, such as 0x4200…0006 on Base and Optimism. Apps on that network expect this address.

Bridged WETH

Bridged WETH is a token that represents ETH moved from Ethereum by a bridge, at its own contract on the destination network, such as WETH on BNB Chain or WETH.e on Avalanche. Its backing depends on the bridge.

Contract address

A contract address is the 0x address of a token contract. WETH has a different one on every network, and a token named WETH at any other address is not WETH. WETH not showing.

Gas

Gas is the unit of computation a transaction uses; the fee is gas used times gas price and is paid in the network’s native token, never in WETH. On Polygon the gas token is POL. WETH and gas.

Lookalikes and Neighbours

aWETH

aWETH is the receipt token Aave mints when you deposit WETH into its lending pool. It represents a lending position that earns interest, not WETH itself. WETH lookalikes.

WETH.e

WETH.e is Wrapped Ether bridged to Avalanche through the Avalanche Bridge; the “.e” suffix marks an Ethereum-bridged asset at its own contract.

Liquid staking token (LST)

A liquid staking token represents ETH staked with a protocol and earns staking rewards, so its value is not tied 1:1 to ETH the way WETH is. WETH vs liquid staking tokens.

stETH

stETH is Lido’s liquid staking token: its balance grows daily with staking rewards, and its market price can drift slightly from 1 ETH. stETH vs WETH.

wstETH

wstETH is wrapped stETH: a fixed balance whose ETH value rises over time instead of the balance itself. wstETH vs WETH.

cbETH

cbETH is Coinbase’s token for ETH staked through Coinbase; one cbETH converts to more than one ETH as rewards accrue. cbETH vs WETH.

Trading and Wallets

DEX (decentralized exchange)

A DEX is a set of smart contracts that swaps tokens from liquidity pools without an operator holding your funds, such as Uniswap or Curve. Almost all WETH trading happens on DEXs.

Slippage

Slippage is the difference between the quoted and the executed price of a swap, caused by the pool price moving. A wrap or unwrap has none, because its rate is fixed at 1:1.

Self-custody wallet

A self-custody wallet keeps the private keys on your device, so only you can sign transactions with your WETH and ETH. Gem Wallet, for example, is a self-custody wallet that wraps and unwraps ETH and WETH inside the app.

Every term above links to the page that owns it; start from what WETH is or the WETH contract addresses.