GlossaryIntermediate
Post-Only Order
An order instruction guaranteeing it will only ever add liquidity as a maker order, automatically canceling rather than executing as a taker.
A post-only order is an order instruction guaranteeing it will only ever execute as a maker order (see Kaavon's "Maker Order" glossary definition) — if the order would otherwise immediately match an existing order and execute as a taker instead, it's automatically canceled rather than filled.
Traders use post-only orders specifically to guarantee they pay the lower maker fee under a maker-taker fee model (see Kaavon's "Maker-Taker Fee Model" glossary definition), accepting the trade-off that the order might not execute at all if market conditions change before it can be placed as a genuine maker order.
Examples
- A post-only order that would otherwise execute immediately against an existing order is automatically canceled instead of filled, guaranteeing it never pays the higher taker fee.
- Traders use post-only orders specifically to guarantee the lower maker fee, accepting the risk that the order might not execute at all.