What is 0x Protocol?
0x crypto usually means the 0x Protocol, an open protocol and set of developer tools for trading tokens on blockchains. It began in 2017 as a way to trade Ethereum tokens peer to peer, and the ZRX token launched that year.
Today 0x describes itself as onchain routing infrastructure for digital assets. Its site lists four products as of 2026: Swap API, Cross-Chain API, Gasless API and Trade Analytics API. Its docs list 22 EVM chains for the Swap API, including Ethereum, Base and Polygon.
Matcha is a consumer trading product built on 0x infrastructure. It is separate from the protocol itself. A DEX (Decentralized Exchange) built on 0x relies on Smart Contract code to settle trades, so users keep custody of their tokens until the swap executes.
How 0x order matching and liquidity sourcing work
The Swap API is described in the 0x docs as a DEX aggregation and smart order routing API. It asks several liquidity sources for quotes at once, compares them and returns the best price. It can also split one trade across sources. The API returns an unsigned transaction that the app asks the user to sign.
On-chain liquidity
On-chain sources are pools in public AMM (Automated Market Maker) protocols. The docs name Uniswap, Curve, SushiSwap and PancakeSwap among them.
Request for quote (RFQ)
Off-chain sources are professional market makers. Through the RFQ system they return signed quotes at their own discretion. A maker quote is used only when it beats the AMM quotes. Each RFQ order names a specific taker address, so only that address can fill it. Access depends on the integrator's plan.
From quote to settlement
- The app requests a price or quote from the Swap API.
- 0x compares AMM and market maker sources and returns a route.
- The user approves the spender address that the API returns, usually the AllowanceHolder contract.
- The app sends the swap data to the Settler contract, which executes the trade.
Contract addresses can change. 0x docs say to read the Settler address from the API response, and never to set token allowances on the Settler itself, because funds may be lost.
What the ZRX token is used for
ZRX is an ERC-20 token that launched in 2017. Secondary guides describe a hard cap of one billion tokens. ZRX was originally used for protocol governance, staking and relayer fees.
Governance is a different story today. In its support guidance, 0x says governance is currently dormant. It links this to the mid-2024 rollout of the Settler contracts, which left the older Exchange Proxy contract effectively retired. 0x does not expect governance to resume soon.
- Governance: Historically ZRX holders voted on protocol changes. As of 2026, 0x describes this as dormant.
- Staking: 0x points ZRX stakers who want to withdraw to a community-published unstaking guide that its security team has reviewed.
- Trading: ZRX remains a token that trades on exchanges.
Holding ZRX does not give a claim on 0x revenue or on active governance today. This page is educational, not investment advice. Check the official 0x help centre.
0x vs other DEX infrastructure
DEX infrastructure comes in different layers. 0x sits mainly in the routing layer, so it often sends trades to AMMs instead of competing with them.
| Layer | Example | Core job |
|---|---|---|
| Aggregator and routing API | 0x Swap API | Compares many sources and returns one route |
| AMM protocol | Uniswap, Curve | Token pools priced by a formula |
| Consumer trading app | Matcha | User interface that uses 0x routing |
| Market maker quotes | 0x RFQ | Signed off-chain quotes from professional makers |
0x does not hold the main pools. It connects apps to many liquidity sources, including AMMs and market makers.
Frequently asked questions
What is ZRX used for?
ZRX was designed as the 0x Protocol token for governance, staking and relayer fees. As of 2026, 0x says protocol governance is dormant and does not expect it to resume soon. ZRX still exists as an ERC-20 token that trades on exchanges, but you do not need it to use 0x products such as the Swap API.
Is 0x a DEX?
Not exactly. 0x is infrastructure that developers use to build exchanges and trading apps. Its Swap API aggregates liquidity from AMMs such as Uniswap and Curve and from market makers. Apps built on it, such as Matcha, give users an interface, while the 0x contracts settle each trade on-chain without holding user funds.
Related terms
- DEX (Decentralized Exchange)
- AMM (Automated Market Maker)
- ERC-20
- Smart Contract
Sources
- 0x Swap API overview 0x
- About the RFQ System 0x
- Supported Chains and Providers 0x
- Contracts: Settler, AllowanceHolder and Permit2 0x
- 0x docs FAQ 0x
- How to get support for 0x protocol, 0x governance, or ZRX staking questions 0x Help Center
- 0x homepage 0x
- 0x Protocol and ZRX Guide: Swap API, Settler and Governance Status Boxmining (secondary source)
This glossary entry is for general information and education only. It is not investment, tax or legal advice. Crypto assets are high-risk; check official sources before you act.