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Every OCX venue runs a central limit order book (CLOB) with price-time priority: the best price trades first, and at the same price the earlier order trades first. This page covers the order options you can set, what happens across an order’s life, and how fees are charged.

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Order types

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type
string
limit rests at a price you set. market executes immediately against the book at the best available prices.
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side
string
buy or sell.
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timeInForce
string
How long an order stays active: gtc rests until filled or cancelled, ioc fills what it can immediately then cancels the rest, fok fills fully or cancels entirely.
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postOnly
boolean
Rejects the order if it would take liquidity — guarantees you stay on the maker side.
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reduceOnly
boolean
Prevents the order from increasing your position — used for exit-only orders.
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clientOrderId
string
Your own id for idempotent tracking of an order.
Perpetuals and futures additionally accept a marginMode (isolated or cross) and optional protective triggers (stopPrice, takeProfitPrice, stopLossPrice).

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Preview before you trade

Every order endpoint has a preview sibling that dry-runs the order with no side effects. It returns the notional, estimated fee, your fee role and tier, the margin required, and whether the order would be approved. Use it to size safely. 
curl -b cookies.txt -X POST "https://<api-host>/perps/orders/preview" \
  -H "Content-Type: application/json" \
  -d '{ "marketId":"BTC-PERP","side":"buy","type":"limit","price":"68000","quantity":"0.5" }'

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Placing orders

curl -b cookies.txt -X POST "https://<api-host>/perps/orders" \
  -H "Content-Type: application/json" \
  -d '{ "marketId":"BTC-PERP","side":"buy","type":"limit","price":"68000","quantity":"0.5","timeInForce":"gtc","postOnly":true }'
Perp and futures orders share the same API (/perps/orders). Option and spot orders use /orders (with an /options/orders alias). Multi-leg option strategies use /orders/strategy.

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Multi-leg option strategies

Combine 2–8 option legs into a single strategy (for example a call spread or straddle). Strategies are all-or-none-immediate: every leg must fully fill or the whole strategy is rejected. 
curl -b cookies.txt -X POST "https://<api-host>/orders/strategy" \
  -H "Content-Type: application/json" \
  -d '{
    "strategyName": "call-spread",
    "legs": [
      { "market": "BTC-2026-05-15-40000-C", "side": "buy",  "quantity": "5", "price": "1240" },
      { "market": "BTC-2026-05-15-45000-C", "side": "sell", "quantity": "5", "price": "430" }
    ]
  }'

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Order lifecycle

1

Submit

You place (or preview) an order. It passes a margin check before acceptance; a rejected order returns an insufficient-margin error.
2

Match or rest

A marketable order matches immediately against the book. Any unfilled remainder either rests (gtc), cancels (ioc), or voids the whole order (fok). A postOnly order that would take liquidity is rejected outright.
3

Fill

As the order executes, fills are generated. Each fill records its price, quantity, and whether you were the maker or taker (liquidity). Fills update your position in real time.
4

Amend or cancel

Cancel one order by id, cancel all your orders (optionally scoped to a market), and for options amend a resting order’s price or quantity.
Cancellation endpoints: 
curl -b cookies.txt -X POST "https://<api-host>/perps/orders/<id>/cancel"

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Fees: the maker–taker model

OCX uses a standard maker–taker fee model with volume-based tiers — the higher your rolling 30-day volume, the better your rates. On the top tiers the maker side can be a rebate (a negative maker fee), rewarding you for providing liquidity.
  • Maker — your order rests on the book and is filled by someone else. Lower fee, and potentially a rebate.
  • Taker — your order removes liquidity from the book. Higher fee.
Query the live schedule rather than hardcoding it: 
curl "https://<api-host>/perps/fees"
# -> [ { "min30dVolumeUsd": ..., "makerBps": ..., "takerBps": ... }, ... ]
Your personal tier, fee role, and estimated fee for a specific order are all returned by the order preview endpoint — the most reliable way to know what you’ll pay before trading. Options have their own schedule at GET /options/fees.