What Is 0x Protocol?
0x Protocol is a set of rules, implemented as smart contracts on the Ethereum blockchain, that lets people trade ERC-20 tokens directly with one another without a central company holding their funds. Developers can build trading applications on top of it, and many decentralized exchange platforms use it for part of their order matching. The protocol's native token is ZRX.
How It Works
Traders create orders off-chain and sign them with their wallet. A signed order states which tokens are offered, which tokens are wanted in return, the price, and an expiry time. Because the signature proves the trader's intent, the order can be shared publicly and listed in an order book run by third parties called relayers, rather than being posted to the blockchain right away. When another user chooses to fill an order, the trade is settled on-chain. The smart contract checks the signature, price, and expiry before moving the tokens.
Relayers often charge fees for hosting orders. The protocol is designed so that anyone can run a relayer or build an interface, which separates the order-sharing layer from the settlement layer.
Why It Matters to Investors
Because settlement happens on-chain, users keep control of their assets until a trade executes. This can reduce the risk of a platform losing customer deposits. Off-chain order sharing also avoids paying blockchain transaction fees for orders that are never filled.
Risks and Limitations
Users still face smart contract risk, since bugs or exploits in code can cause losses. Liquidity on any single relayer may be thin, which can lead to slippage. Order books can also be incomplete, because a signed order remains available only until it is filled, cancelled, or expires. The price of ZRX, like other crypto assets, can be highly volatile, and the token's role within the protocol can change over time.
Updated October 14, 2026. For general education only; not financial, tax or legal advice.