> For the complete documentation index, see [llms.txt](https://docs.asterdex.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.asterdex.com/trading/perpetuals/order-types/chase-order.md).

# Chase Order

A chase order is a limit order that automatically updates its price to follow the best bid or ask, so you stay in line with the market without manually re-pricing. The order keeps running until it fills, you cancel it, or the price moves past a max chase difference you set.

All chase orders are placed as post-only, so every fill is a maker fill at Aster's 0 maker fee. Aster is the first DEX with native chase orders, built into the matching engine and verifiable on Aster Chain.

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### How it works

Every second, the system checks the best bid/ask and updates your order price if necessary. Only the price is updated — quantity cannot change. Updated orders re-enter the order book queue at the corresponding price level.

You can configure a chase order in two ways:

**Best bid/ask** — the order price follows the best bid or best ask directly. This gives you the fastest fill at the most aggressive available price.

**Gap from best bid/ask** — the order maintains a fixed distance from the best bid or best ask. You get a better entry price at the cost of slower fills.

In both modes, you can set a max chase difference. If the market moves past that boundary, the order automatically cancels instead of continuing to chase.

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### Two modes

**Best bid / ask** Places your order at the front of the book. Gives you the fastest fill at the most aggressive available price.

* Buy: price updates to Bid1 whenever Bid1 rises above the current order price.
* Sell: price updates to Ask1 whenever Ask1 falls below the current order price.

**Gap from best bid / ask** Places your order at a fixed distance behind the book, set as an absolute price gap. You get a better entry price at the cost of slower fills.

* Buy: price = Bid1 − offset, updating whenever Bid1 − offset rises above the current order price.
* Sell: price = Ask1 + offset, updating whenever Ask1 + offset falls below the current order price.

In both modes, you can set a max chase difference. If the market moves past that boundary, the order automatically cancels instead of continuing to chase.

### Max chase difference

This setting limits how far an order can follow the market price. If the market moves past the boundary you set, the order is automatically cancelled by the system.

You can set the max chase difference as an absolute price distance or a percentage.

**Buy orders**

* Absolute: max chase price = original Bid1 + offset
* Percentage: max chase price = original Bid1 × (1 + offset%)
* Cancellation triggers when the latest order price exceeds the max chase price.

**Sell orders**

* Absolute: min chase price = original Ask1 − offset
* Percentage: min chase price = original Ask1 × (1 − offset%)
* Cancellation triggers when the latest order price falls below the min chase price.

### Order rules

Active order limit Each user can run up to 5 active chase orders per trading pair. Additional orders will be rejected if the limit is reached.

Manual modification Chase orders cannot be modified after submission. To change parameters such as quantity, chase gap, or max chase difference, cancel the order and place a new one.

### How to use

Available under Perpetuals → Order type → Chase Order. REST API is also available for systematic traders.

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