0x Documentation
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API References
Learn how to use the 0x API, a REST API that runs on HTTP

Introduction

The 0x 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.
While the 0x Labs Team hosts a version of the 0x API (subject to the 0x Terms of Service), all the code is open source and available at the 0x-API GitHub repo. If you run into a problem, don't hesitate to open an issue.
We offer hosted versions for different Ethereum networks. Requests for more networks, and questions/feedback in general should be directed at our Discord.
Network
Endpoint
Ethereum (Mainnet)
Ethereum (Goerli)
Ethereum (Ropsten)*
Polygon
Polygon (Mumbai)
Binance Smart Chain
Optimism
Fantom
Celo
Avalanche
Arbitrum
*We will support Ropsten testnet until October 25, 2022 as this testnet has already been deprecated by the Ethereum Foundation. Developers should plan to migrate to Goerli by that date.

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.

Pagination

Requests that return potentially large collections are paginated and respond to the page and perPage parameters. For example:
https://api.0x.org/sra/v4/orders?page=3&perPage=20
Any endpoint that follows this convention will display the following:
This endpoint is paginated.
And will only document the objects in the records field.

Request

Query Param
Description
page
(Optional, defaults to "1") The page index (1-indexed) requested in the collection.
perPage
(Optional, defaults to "20") The amount of records to return per page. The maximum is "1000".

Response

Field
Description
page
The page index (1-indexed) of returned in the response (same as request if provided).
perPage
The amount of records requested in the pagination, but not necessarily returned.
total
The total amount of records in the collection (across all pages).
records
The actual records returned for this page of the collection.
If a query provides an unreasonable (ie. too high) perPage value, the response can return a validation error as specified in the errors section. If the query specifies a page that does not exist (ie. there are not enough records), the response will return an empty records array.

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 the0x Cheat Sheet .
Network
ExchangeProxy Address
ERC20Proxy Address
StakingProxy Address
Ethereum (mainnet)
0xdef1c0ded9bec7f1a1670819833240f027b25eff
0x95e6f48254609a6ee006f7d493c8e5fb97094cef
0xa26e80e7dea86279c6d778d702cc413e6cffa777
Ethereum (ropsten)
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

Errors

Unless the spec defines otherwise, errors to bad requests should respond with HTTP 4xx or status codes.

Common Error Codes

Code
Reason
400
Bad Request – Invalid request format
404
Not found
429
Too many requests - Rate limit exceeded
500
Internal Server Error
501
Not Implemented
503
Server Error - Too many open connections

Error reporting format

For all 400 responses, see the error response schema.
{
"code": 101,
"reason": "Validation failed",
"validationErrors": [
{
"field": "maker",
"code": 1002,
"reason": "Invalid address"
}
]
}

General error codes

Code
Reason
100
Validation Failed
101
Malformed JSON
102
Order submission disabled
103
Throttled
104
Not Implemented
105
Transaction Invalid

Validation error codes

Code
Reason
1000
Required field
1001
Incorrect format
1002
Invalid address
1003
Address not supported
1004
Value out of range
1005
Invalid signature or hash
1006
Unsupported option
1007
Invalid 0x order
1008
Internal error
1009
Token is not supported
1010
Field is invalid

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.
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On this page
Introduction
Versioning
Pagination
Allowance Targets
Addresses by Network
Errors
Common Error Codes
Error reporting format
Common Objects
Signed Order
Signature
Misc.