Transaction Simulation FAQs

Find answers to frequently asked questions related to Alchemy's Transaction Simulation APIs

What chains do you support?

ChainNetwork
EthereumMainnet
EthereumGoerli
EthereumSepolia
PolygonMainnet
PolygonMumbai
ArbitrumMainnet
ArbitrumGoerli
OptimismMainnet
OptimismGoerli

Wrapped tokens

NetworkNameContract Address
Eth MainnetWETH0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2
Eth GoerliWETH0xb4fbf271143f4fbf7b91a5ded31805e42b2208d6
Polygon MainnetWMATIC0x0d500b1d8e8ef31e21c99d1db9a6444d3adf1270
Polygon MumbaiWMATIC0x9c3c9283d3e44854697cd22d3faa240cfb032889
Arbitrum MainnetWETH0x82af49447d8a07e3bd95bd0d56f35241523fbab1
Arbitrum GoerliWETH0x1dfc378641f06f4095e9434017bf335018550c55

Do you support NFTs that predate ERC721?

Yes.

We recently added support for the following NFTs that predate the ERC721 standard:

  • CryptoKitties
  • Cryptopunks

assetType will be set to SPECIAL_NFT for these collections.

This is consistent with our Transfers API.

NetworkNameContract Address
Eth MainnetCryptoKitties0x06012c8cf97bead5deae237070f9587f8e7a266d
Eth MainnetCryptoPunks0xb47e3cd837ddf8e4c57f05d70ab865de6e193bbb

How can I get metadata for NFTs (ERC721, ERC155)?

You can use the collection address (contractAddress) and token id (tokenId) returned in the response to call our getNFTMetadata endpoint - see here.


How can I determine if a simulation was successful?

You can check if the top level error field is null.


How can I get gas used?

alchemy_simulateAssetChanges

You can access the top level gasUsed field.

alchemy_simulateExecution

The API can return a flat or a nested response depending on the 3rd parameter passed in the request (defaults to flat response).

Flat response - gasUsed in first call.

Nested response - gasUsed in root call of nested response.


Simulation Limits and Pricing

  • Free tier users have access to up to 1000 simulations per day.
  • Growth tier users have access to up to 50,000 simulations per day.
  • Enterprise tier users can perform unlimited simulations.

Please note that bundle simulation is only available on the Growth and Enterprise tiers.