# Transaction Simulation FAQs

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

> For the complete documentation index, see [llms.txt](/docs/llms.txt).

## What chains do you support?

<Info>
  Check the [Chains](https://dashboard.alchemy.com/signup) page for details about product and chain support!

  ![](https://alchemyapi-res.cloudinary.com/image/upload/v1764179964/docs/api-reference/alchemy-transact/transaction-simulation/523fb8a9a9d899921ee1046d0ff1b389967a9976d1c6112ebbbe071ddd1ef374-image.png)
</Info>

## Wrapped tokens

| Network          | Name   | Contract Address                           |
| ---------------- | ------ | ------------------------------------------ |
| Eth Mainnet      | WETH   | 0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2 |
| Eth Goerli       | WETH   | 0xb4fbf271143f4fbf7b91a5ded31805e42b2208d6 |
| Polygon Mainnet  | WMATIC | 0x0d500b1d8e8ef31e21c99d1db9a6444d3adf1270 |
| Polygon Mumbai   | WMATIC | 0x9c3c9283d3e44854697cd22d3faa240cfb032889 |
| Arbitrum Mainnet | WETH   | 0x82af49447d8a07e3bd95bd0d56f35241523fbab1 |
| Arbitrum Goerli  | WETH   | 0x1dfc378641f06f4095e9434017bf335018550c55 |

***

## 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](/docs/reference/transfers-api-quickstart#6-special-nft-transfers).

| Network     | Name          | Contract Address                           |
| ----------- | ------------- | ------------------------------------------ |
| Eth Mainnet | CryptoKitties | 0x06012c8cf97bead5deae237070f9587f8e7a266d |
| Eth Mainnet | CryptoPunks   | 0xb47e3cd837ddf8e4c57f05d70ab865de6e193bbb |

***

## 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](/docs/reference/getnftmetadata).

***

## 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 1,000 simulations per day.
* Growth tier users have access to up to 50,000 simulations per day.
* Scale tier users have access to up to 75,000 simulations per day.
* Enterprise tier users can perform unlimited simulations.

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