Encyclopedia DeFi · Entry 333
Post-only orders: requiring a maker order instead of an immediate fill
In this article
At a glance
Key facts
| Fact | Detail | Source |
|---|---|---|
| Maker intent | The order should rest on the book. | [1] |
| Crossing | A dYdX post-only order is cancelled if it immediately matches an existing order. | [1] |
| Separate price | The limit price still bounds acceptable execution. | [1] |
A competitive price can conflict with maker-only status
Imagine the lowest ask is 100 B per A. A normal buy limit at 101 can immediately buy that ask. A post-only buy at 101 would cross the book, so under the documented rule it is cancelled rather than filled.
A buy at 99 may rest, but another trader still needs to sell into it. The book can also move between a preview and submission.
Maker classification is not a return promise
Post-only can prevent unintended taker execution under its specific rules. The actual maker fee or rebate depends on the venue and account schedule. A maker fill can still be followed by an adverse price move, so a favorable fee alone does not establish a profitable trade.
Check other constraints separately
A resting order can have expiry and cancellation rules. Reduce-only is a different constraint on position exposure and is not automatically implied by post-only. In the cited dYdX guide, reduce-only requires IOC, illustrating why not every combination of familiar order flags is valid.
Direct answers
Questions people ask
If a post-only order disappears, did it necessarily trade?
No. It may have been cancelled for crossing the book, expired or been cancelled for another reason. Check the filled quantity and execution history.
Inspect the evidence
The answer and key facts have stable claim links. These records retain the scope and qualification when reused.
A post-only order is intended to add resting liquidity rather than immediately match an existing order. In the documented dYdX behavior, an order that would match any existing quantity is cancelled instead of taking that liquidity. Post-only constrains execution style; it does not guarantee a future fill or a positive maker rebate.
Scope: DeFi · data through 2026-10-02. Verification: verified · 2026-10-02T19:18:00.092Z.
Link to this claimMaker intent: The order should rest on the book.
Scope: DeFi · data through 2026-10-02. Verification: verified · 2026-10-02T19:18:00.092Z.
Link to this claimCrossing: A dYdX post-only order is cancelled if it immediately matches an existing order.
Scope: DeFi · data through 2026-10-02. Verification: verified · 2026-10-02T19:18:00.092Z.
Link to this claimSeparate price: The limit price still bounds acceptable execution.
Scope: DeFi · data through 2026-10-02. Verification: verified · 2026-10-02T19:18:00.092Z.
Link to this claimRevision history
- — First publication after primary-source research and separate automated verification.
Source register
Sources and references
Retrieval dates and locators are recorded individually.- Perpetual order types on dYdX ChaindYdX Operations Services
Order-type semantics and dYdX-specific constraints.
Locator: Market; Limit; Stop; Take Profit; execution policies · Version / scope: Documentation retrieved for the 2026-10-02 editorial scope; content hash recorded · Retrieved: 2026-10-02T18:53:20.714ZOpen source - Reduce Only OrderdYdX Operations Services
Version-scoped IOC requirement and reduction behavior.
Locator: Requirements; How it works · Version / scope: Documentation retrieved for the 2026-10-02 editorial scope; content hash recorded · Retrieved: 2026-10-02T18:53:20.744ZOpen source - Interface of the Trade tabdYdX Operations Services
Definition and presentation of trading market metrics.
Locator: Orderbook; Position information; Stats · Version / scope: Documentation retrieved for the 2026-10-02 editorial scope; content hash recorded · Retrieved: 2026-10-02T18:53:20.712ZOpen source
Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.
Editorial method and correctionsDegrees of Satoshi editorial project. “Post-only orders: requiring a maker order instead of an immediate fill.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/post-only-orders/