Does the 0x Swap API cost anything through BlockRun?

No. Price, quote, submit and status are free for callers: this is the one service on the site with no payment header. The rate card on this page reads Free.

What is a gasless swap on 0x?

A swap where the 0x relayer pays gas: you sign an EIP-712 message for the trade (and optionally the approval) instead of broadcasting a transaction. It is the flow for an agent that holds the sell token but no gas.

What is a Permit2 swap?

The standard flow: get a firm quote, sign one EIP-712 Permit2 message, broadcast the returned transaction from a wallet that pays gas.

Which chains does the 0x Swap API support?

The chains endpoint on this page lists them at request time, and the gasless-tokens endpoint says which tokens are eligible for the gasless flow, so a client can fail fast before quoting.

Does the 0x endpoint execute the swap for me?

No. It prices and routes across many DEXes and returns a transaction or typed data to sign; your wallet signs and submits. Nothing here holds funds.

0x via BlockRun vs 1inch, Jupiter or Uniswap's routing API?

Each needs its own key, with per-key rate limits and a paid tier on some. This is 0x's routing reached with no key and no limit, free for callers, returning the same transaction or typed data to sign.

Can an AI trading agent rebalance a portfolio through 0x here?

Yes. Quote, sign with the agent's wallet, submit — one quote, one signature, one transaction — with the gasless flow when the agent holds no gas token.

How do I use the 0x Swap API without a 0x API key?

Call BlockRun's swap endpoint. It proxies 0x's Swap and Gasless APIs as a public passthrough — BlockRun holds the upstream key, your agent sends no header, no auth and no payment.

All Services By capability: DEX Aggregator API

DEX TRADING · PARTNER

0x Swap

DEX aggregation for AI agents — Permit2 + Gasless V2

BlockRun proxies the 0x V2 Swap and Gasless V2 APIs as a free public passthrough. No API key required from your agent, no x402 payment, no subscription — point your agent at the gateway and call any endpoint.

11 endpoints live

Free public passthrough

Website 0x Swap API Docs Live capability check

Capabilities

Permit2 Swap V2

Best-execution swap routing across 100+ DEXes via Permit2. Get a firm quote, sign one EIP-712, broadcast — your wallet pays gas.

Gasless V2

Sign trade.eip712 (and an optional approval.eip712) and the 0x relayer pays gas. Ideal for agents that hold the sell token but no ETH.

No API Keys

BlockRun holds the upstream 0x key server-side. Your agent calls the endpoint directly — no header, no auth, no rate-limit account.

Capability Discovery

Helper endpoints list supported chains and gasless-eligible tokens, so your client can fail fast before quoting.

What AI Agents Use It For

Any agent that needs to convert one token to another — rebalance a portfolio, take profit, top up gas, settle revenue. Standard Swap V2 when the agent has gas; Gasless V2 when it doesn't.

Agent Rebalances to a Target Allocation

wallet pays gas

Agent receives a rebalance instruction and converts USDC → WETH on Base. One quote, one signature, one tx.

quoteUSDC → WETH, sellAmount in base units

signPermit2 EIP-712 with taker wallet

submitbroadcast tx — wallet pays gas

Gasless DCA Without ETH

zero ETH required

Agent dollar-cost-averages into ETH from a USDC balance, but holds no ETH for gas. Use Gasless V2 — sign trade + approval EIP-712s, BlockRun forwards to 0x's relayer, the relayer pays gas.

gasless/quotereturns trade.eip712 + optional approval

gasless/submitPOST signed trade — relayer pays gas

gasless/statuspoll tradeHash until confirmed

Take-Profit on a Position

single quote

Position breaches a take-profit threshold. Agent quotes the inverse pair, signs Permit2, broadcasts. No subscription, no per-month minimum, no key rotation.

priceindicative — surface to UI before commit

quotefirm quote when user confirms

submitbroadcast tx

Pre-flight Eligibility Check

free

Before quoting on a chain you haven't routed before, probe the helper endpoints. Both chain lists and the gasless-approval-tokens list are free passthrough GETs.

swap/chainsis this chain supported at all

gasless/approval-tokenscan sellToken use Permit gasless flow

Pricing

BlockRun does not charge the caller. Free public passthrough — no API keys, no x402 payment, no subscription. Implementation details for integrators are in the API reference.

caller pays BlockRun

free public passthrough

API Reference

Base URL: https://blockrun.ai/api/v1/zerox/

All endpoints are direct passthroughs to api.0x.org. No Authorization or 0x-api-key header is needed from the caller. Request and response shapes match the upstream 0x V2 spec verbatim.

Endpoint	Method	Description
`/api/v1/zerox/price`	GET	Indicative Permit2 swap quote (no commitment).
`/api/v1/zerox/quote`	GET	Firm Permit2 swap quote with permit2.eip712 + tx data.
`/api/v1/zerox/gasless/price`	GET	Gasless indicative price quote.
`/api/v1/zerox/gasless/quote`	GET	Gasless firm quote — returns trade.eip712 (+ optional approval.eip712) for client to sign.
`/api/v1/zerox/gasless/submit`	POST	Submit signed gasless trade (+ optional approval). 0x relayer pays gas; client gets a tradeHash to poll.
`/api/v1/zerox/gasless/status/{...}`	GET	Poll status of a gasless trade by tradeHash. Path = /gasless/status/{tradeHash}.
`/api/v1/zerox/gasless/approval-tokens`	GET	List tokens that support gasless approval (Permit) on a given chain. Use to check if a sell-token can use the fully-gasless flow before quoting.
`/api/v1/zerox/gasless/chains`	GET	List chains where the Gasless API is supported.
`/api/v1/zerox/swap/chains`	GET	List chains where the Swap API is supported.

Quick Start

Permit2 quote on Base — 10 USDC → WETH:

# Indicative price (no commitment, no signature needed)
curl "https://blockrun.ai/api/v1/zerox/price?\
chainId=8453&\
sellToken=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&\
buyToken=0x4200000000000000000000000000000000000006&\
sellAmount=10000000&\
taker=0xYourAgentWallet"

# Firm quote — same params, returns permit2.eip712 + tx data
curl "https://blockrun.ai/api/v1/zerox/quote?\
chainId=8453&\
sellToken=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&\
buyToken=0x4200000000000000000000000000000000000006&\
sellAmount=10000000&\
taker=0xYourAgentWallet"

# Gasless flow — agent has no ETH for gas
curl "https://blockrun.ai/api/v1/zerox/gasless/quote?\
chainId=8453&\
sellToken=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&\
buyToken=0x4200000000000000000000000000000000000006&\
sellAmount=10000000&\
taker=0xYourAgentWallet"
# → sign trade.eip712 (+ optional approval.eip712), POST to /gasless/submit,
#   poll /gasless/status/{tradeHash}

Full request/response shapes: 0x Swap (DEX) — API Reference.

Start swapping with 0x

Point your agent at https://blockrun.ai/api/v1/zerox/ and call any endpoint. No registration, no API keys, no SDK install.

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0x Swap API questions: routing, gasless, chains, cost

Does the 0x Swap API cost anything through BlockRun?: No. Price, quote, submit and status are free for callers: this is the one service on the site with no payment header. The rate card on this page reads Free.
What is a gasless swap on 0x?: A swap where the 0x relayer pays gas: you sign an EIP-712 message for the trade (and optionally the approval) instead of broadcasting a transaction. It is the flow for an agent that holds the sell token but no gas.
What is a Permit2 swap?: The standard flow: get a firm quote, sign one EIP-712 Permit2 message, broadcast the returned transaction from a wallet that pays gas.
Which chains does the 0x Swap API support?: The chains endpoint on this page lists them at request time, and the gasless-tokens endpoint says which tokens are eligible for the gasless flow, so a client can fail fast before quoting.
Does the 0x endpoint execute the swap for me?: No. It prices and routes across many DEXes and returns a transaction or typed data to sign; your wallet signs and submits. Nothing here holds funds.
0x via BlockRun vs 1inch, Jupiter or Uniswap's routing API?: Each needs its own key, with per-key rate limits and a paid tier on some. This is 0x's routing reached with no key and no limit, free for callers, returning the same transaction or typed data to sign.
Can an AI trading agent rebalance a portfolio through 0x here?: Yes. Quote, sign with the agent's wallet, submit — one quote, one signature, one transaction — with the gasless flow when the agent holds no gas token.
How do I use the 0x Swap API without a 0x API key?: Call BlockRun's swap endpoint. It proxies 0x's Swap and Gasless APIs as a public passthrough — BlockRun holds the upstream key, your agent sends no header, no auth and no payment.