Post-Only Order: What It Is and Why It Matters in Crypto and Trading

When you trade crypto, a post-only order, a type of limit order that can’t immediately match with existing orders on the order book. Also known as maker-only order, it’s designed to add liquidity instead of taking it away. This small rule changes how you interact with exchanges, reduces fees, and keeps you out of risky trades. Most major platforms like Binance, Kraken, and Bybit use post-only rules to encourage market makers—traders who place bids and asks that others can fill—rather than high-frequency takers who snap up existing orders.

Why does this matter? Because if you place a regular limit order that hits an existing bid or ask, you’re charged a taker fee—often higher than the maker fee you’d pay if your order sat on the book. A post-only order, forces your order to only execute if it doesn’t immediately match. Also known as maker-only, it’s built into the exchange’s matching engine to prevent accidental price-sniping. If your order would have filled right away, the system rejects it. You don’t get charged. You don’t get filled. You just try again with a better price. This protects you from slippage in fast-moving markets and keeps your trading costs low.

It’s not just about saving money. In DeFi and crypto markets, where liquidity can vanish in seconds, post-only orders help stabilize price action. They prevent bots from exploiting thin order books by snapping up every available sell order. That’s why platforms like Uniswap V3 and dYdX use similar logic behind the scenes—rewarding traders who provide depth instead of those who drain it. Even in stock markets, hedge funds rely on this mechanism to avoid paying premiums during volatility spikes.

But here’s the catch: if you’re trying to get into a trade fast, a post-only order might never fill. That’s fine—if you’re a long-term holder or a liquidity provider, you don’t need to rush. But if you’re scalping or chasing pumps, you’ll need to switch to regular limit or market orders. The key is knowing when to use each. Most trading tools let you toggle post-only mode with a single click. Use it when you’re patient. Skip it when you’re in a hurry.

You’ll find posts below that dig into how order books work in crypto, why exchanges charge different fees for makers and takers, and how bots manipulate liquidity to trap retail traders. Some cover how platforms like Aave and Compound handle order types in lending markets. Others break down real cases where post-only rules saved traders from bad fills during flash crashes. Whether you’re new to trading or you’ve been in the game for years, understanding this one setting can cut your costs and improve your edge.