API References

Introduction

The Swap API is the liquidity and data endpoint for DeFi. It lets you access aggregated liquidity from tens of on-chain and off-chain decentralized exchange networks, across multiple blockchains. It comes with many parameters to customize your requests for your application and your users.

We offer hosted versions for different EVM-compatible networks.

Network	Endpoint
Ethereum (Mainnet)	https://api.0x.org/
Ethereum (Sepolia)	https://sepolia.api.0x.org/
Polygon	https://polygon.api.0x.org/
Binance Smart Chain	https://bsc.api.0x.org/
Optimism	https://optimism.api.0x.org/
Fantom	https://fantom.api.0x.org/
Celo	https://celo.api.0x.org/
Avalanche	https://avalanche.api.0x.org/
Arbitrum	https://arbitrum.api.0x.org/
Base	https://base.api.0x.org/

Endpoints

Learn more about the different endpoints of Swap API:

• GET /swap/v1/quote - Get an easy-to-consume quote for buying or selling any ERC20 token. Returns a transaction that can be submitted to an Ethereum node.
• GET /swap/v1/price - /price is nearly identical to /quote, but with a few key differences. /price does not return a transaction that can be submitted on-chain; it simply provides us the same information. Think of it as the "read-only" version of /quote.
• GET /swap/v1/source - Returns the liquidity sources enabled for a specific chain.

Authentication

0x authenticates your API requests using your account’s API keys. Once you’re set up, ensure that you specify your key with the 0x-api-key header parameter in your requests.

You can create, access or revoke your API keys via the 0x Dashboard.

Versioning

Each 0x HTTP API path is versioned independently using URI versioning. The format is: https://api.0x.org/<path>/<version>/<endpoint>.

For example, you can request https://api.0x.org/swap/v1/quote which represents v1 of the quote endpoint in the swap path. URLs not adhering to this format are not supported.

A major version bump occurs whenever a backwards incompatible change occurs to an endpoint, in which case every endpoint in that path will be on the next version. Old versions of the API will be deprecated and new features will be rolled out to them on a best-effort basis.

Allowance Targets

Some interactions with 0x require or are improved by setting token allowances, or in other words, giving 0x's smart contracts permission to move certain tokens on your behalf. Some examples include -

• Submitting a 0x API quote selling ERC20 tokens, you will need to give an allowance to the contract address. This address can be found either as the value of allowanceTarget returned in the quote response or in the ExchangeProxy Address column in the "Addresses by Network" table below.
• Trading ERC20 tokens using the Exchange contract, you will have to give an allowance to the ERC20Proxy contract.
• Note: For swaps with "ETH" as sellToken, wrapping "ETH" to "WETH" or unwrapping "WETH" to "ETH" no allowance is needed, a null address of 0x0000000000000000000000000000000000000000 is then returned instead.

Addresses by Network

The following table includes commonly used contract addresses. For a full list of our smart contract deployments address, see the 0x Cheat Sheet.

Network	ExchangeProxy Address	ERC20Proxy Address	StakingProxy Address
Ethereum (mainnet)	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x95e6f48254609a6ee006f7d493c8e5fb97094cef	0xa26e80e7dea86279c6d778d702cc413e6cffa777
Ethereum (sepolia)	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0xf1ec7d0ba42f15fb5c9e3adbe86431973e44764c	0x6acab4c9c4e3a0c78435fdb5ad1719c95460a668
Polygon	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Binance Smart Chain	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Optimism	0xdef1abe32c034e558cdd535791643c58a13acc10	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Fantom	0xdef189deaef76e379df891899eb5a00a94cbc250	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Celo	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Avalanche	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Arbitrum	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000
Base	0xdef1c0ded9bec7f1a1670819833240f027b25eff	0x0000000000000000000000000000000000000000	0x0000000000000000000000000000000000000000

Errors

See Error codes for a full list of common 0x error codes and how to resolve them.

Common Objects

This section outlines API JSON objects that are common to many endpoints.

Signed Order

A 0x Limit Order with additional fields and ready to be consumed by our tooling and sent to the 0x exchange proxy contract.

Field	Description
maker	The address of the party that creates the order. The maker is also one of the two parties that will be involved in the trade if the order gets filled.
taker	The address of the party that is allowed to fill the order. If set to a specific party, the order cannot be filled by anyone else. If left unspecified, anyone can fill the order.
makerToken	The address of the ERC20 token the maker is selling to the taker.
takerToken	The address of the ERC20 token the taker is selling to the maker.
makerAmount	The amount of makerToken being sold by the maker
takerAmount	The amount of takerToken being sold by the taker
expiry	Timestamp in seconds of when the order expires. Expired orders cannot be filled.
salt	A value that can be used to guarantee order uniqueness. Typically it is set to a random number.
feeRecipient	The address of the entity that will receive any fees stipulated by the order. This is typically used to incentivize off-chain order relay.
pool	The staking pool to attribute the 0x protocol fee from this order. Set to zero to attribute to the default pool, not owned by anyone.
takerTokenFeeAmount	Amount of takerToken paid by the taker to the feeRecipient.
sender	An advanced field that doesn't need to be set. It allows the maker to enforce that the order flow through some additional logic before it can be filled (e.g., a KYC whitelist) -- more on the ability to extend 0x later.
verifyingContract	Address of the contract where the transaction should be sent, usually this is the 0x exchange proxy contract.
chainId	The ID of the Ethereum chain where the verifyingContract is located.
signature	A JSON object with the signature of the fields above using the private key of maker. The fields of the signature object are documented in the table below.

Signature

A structured object containing the signature data for the order. For more info see How to sign.

Field	Description
signatureType	A number representing the signature method used for signing the order, EIP712 (2) and EthSign (3) are supported.
r	A hexadecimal string with signature data.
s	A hexadecimal string with signature data.
v	An integer number with signature data.

Misc.

• All requests and responses should be of "application/json" content type.
• All token amounts are sent in amounts of the smallest level of precision (base units). (e.g if a token has 18 decimal places, selling 1 unit of the token would show up as selling 1000000000000000000 base units by this API).
• All addresses are sent as lower-case (non-checksummed) Ethereum addresses with the 0x prefix.
• All parameters should use lowerCamelCase.