Transaction Simulation FAQs

What chains do you support?

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Wrapped tokens

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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.

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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.

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How can I determine if a simulation was successful?

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

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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.

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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.