# Tokens & fees

# Supported tokens

zkSync can be used to transfer ether (ETH) and ERC20 tokens. Initially, new tokens need to be manually whitelisted by the operator. In the future adding new tokens will be permissionless.

# Fee costs

In zkSync the cost of every transaction has two components:

  • Off-chain part (storage + prover costs): the cost of the state storage and the SNARK (zero-knowledge proof) generation. This part depends on the use of hardware resources and is therefore invariable. Our benchmarks give estimates of ~0.001 USD per transfer.
  • On-chain part (gas costs): for every zkSync block, the validator must pay Ethereum gas to verify the SNARK (~400k gas, amortized across all transactions in the block), plus additionally ~0.4k gas per transaction to publish the state ∆. The on-chain part is variable because it depends on the current gas price in the Ethereum network. However, this part is orders of magnitude cheaper than the cost of normal ETH/ERC20 transfers.

As of today (Apr 17, 2020) the full transfer price is estimated to be ~0.004 USD.

# How fees are payed

Transfers in zkSync work as "gasless meta-transactions": users pay transaction fees in the tokens being transferred. Thus, for example, if you want to transfer DAI stable-coin, there is no need for you to own ETH or any other tokens. Just pay your fees in a fraction of DAI.