Route Orders Across Venues with Kairos Cross-Venue Routing

Cross-venue routing lets you buy or sell a large prediction market position by splitting the order across matched markets on Polymarket and Kalshi at the same time. Instead of exhausting a thin book on one venue or moving the price against yourself, Kairos splits your size across both legs simultaneously — giving you a better average fill price and deeper effective liquidity.

All routing endpoints require the API key triple (X-Client-Id / X-Api-Key / X-Api-Secret). Base URL: https://execution.kairos.trade.

How cross-venue routing works

When Kairos identifies that a market on Polymarket and a market on Kalshi are tracking the same event, it creates a market link — a verified mapping between the two venues. When you route through a link, Kairos:

Computes an optimal split between the two legs based on available liquidity and prices.
Submits orders on both venues simultaneously.
Tracks a parent routed order with two leg orders underneath.
Lets you close the full position in one call.

Step 1 — Create a market link

Before routing, you need a market link connecting the two venues. Use POST /orders/market-links to create or preview one.

curl -X POST "https://execution.kairos.trade/orders/market-links" \
  -H "X-Client-Id: $KAIROS_CLIENT_ID" \
  -H "X-Api-Key: $KAIROS_API_KEY" \
  -H "X-Api-Secret: $KAIROS_API_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "polymarket_market_id": "0xabc123",
    "kalshi_market_id": "FED-25JAN-T0.5",
    "preview": false
  }'

import os
import httpx

API_HEADERS = {
    "X-Client-Id": os.environ["KAIROS_CLIENT_ID"],
    "X-Api-Key": os.environ["KAIROS_API_KEY"],
    "X-Api-Secret": os.environ["KAIROS_API_SECRET"],
}

resp = httpx.post(
    "https://execution.kairos.trade/orders/market-links",
    json={
        "polymarket_market_id": "0xabc123",
        "kalshi_market_id": "FED-25JAN-T0.5",
        "preview": False,
    },
    headers=API_HEADERS,
)
link = resp.json()
link_id = link["link_id"]
print(f"Market link created: {link_id}")

Example response:

{
  "link_id": "lnk_4fPq7rHsKzM1",
  "polymarket_market_id": "0xabc123",
  "kalshi_market_id": "FED-25JAN-T0.5",
  "polymarket_outcome": "YES",
  "kalshi_outcome": "YES",
  "status": "approved",
  "created_at": "2025-01-15T10:00:00Z"
}

Pass "preview": true to validate the link and see the matched outcomes without persisting it. Use this to confirm the mapping is correct before committing.

Many popular matched markets already have pre-approved links. Use GET /orders/route-quote with existing link_id values to check — you may not need to create a new one.

Step 2 — Get a route quote

Before committing to a routed trade, fetch a price quote across both legs. This shows you the expected split, prices on each venue, and total cost.

curl "https://execution.kairos.trade/orders/route-quote?link_id=lnk_4fPq7rHsKzM1&side=buy&size=5000" \
  -H "X-Client-Id: $KAIROS_CLIENT_ID" \
  -H "X-Api-Key: $KAIROS_API_KEY" \
  -H "X-Api-Secret: $KAIROS_API_SECRET"

resp = httpx.get(
    "https://execution.kairos.trade/orders/route-quote",
    params={
        "link_id": "lnk_4fPq7rHsKzM1",
        "side": "buy",
        "size": 5000,
    },
    headers=API_HEADERS,
)
quote = resp.json()
print(quote)

Example response:

{
  "link_id": "lnk_4fPq7rHsKzM1",
  "side": "buy",
  "total_size": 5000,
  "legs": [
    {
      "venue": "polymarket",
      "size": 3200,
      "avg_price": 0.615,
      "cost_usdc": 1968.00
    },
    {
      "venue": "kalshi",
      "size": 1800,
      "avg_price": 0.618,
      "cost_usdc": 1112.40
    }
  ],
  "blended_avg_price": 0.616,
  "total_cost_usdc": 3080.40,
  "total_fees_usdc": 10.78,
  "quote_expires_at": "2025-01-15T14:24:05Z"
}

Review the blended_avg_price and total_cost_usdc before deciding to execute.

Step 3 — Check the fee model

View the per-leg fee structure for a market link before trading:

curl "https://execution.kairos.trade/orders/route-fees?link_id=lnk_4fPq7rHsKzM1" \
  -H "X-Client-Id: $KAIROS_CLIENT_ID" \
  -H "X-Api-Key: $KAIROS_API_KEY" \
  -H "X-Api-Secret: $KAIROS_API_SECRET"

Example response:

{
  "link_id": "lnk_4fPq7rHsKzM1",
  "legs": [
    {
      "venue": "polymarket",
      "platform_fee_rate": 0.0025,
      "exchange_fee_rate": 0.001,
      "total_fee_rate": 0.0035
    },
    {
      "venue": "kalshi",
      "platform_fee_rate": 0.0025,
      "exchange_fee_rate": 0.002,
      "total_fee_rate": 0.0045
    }
  ]
}

Step 4 — Execute the route

When you’re ready to trade, call POST /orders/route-buy. Kairos executes both legs simultaneously.

curl -X POST "https://execution.kairos.trade/orders/route-buy" \
  -H "X-Client-Id: $KAIROS_CLIENT_ID" \
  -H "X-Api-Key: $KAIROS_API_KEY" \
  -H "X-Api-Secret: $KAIROS_API_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "link_id": "lnk_4fPq7rHsKzM1",
    "side": "buy",
    "size": 5000,
    "max_slippage": 0.005
  }'

resp = httpx.post(
    "https://execution.kairos.trade/orders/route-buy",
    json={
        "link_id": "lnk_4fPq7rHsKzM1",
        "side": "buy",
        "size": 5000,
        "max_slippage": 0.005,
    },
    headers=API_HEADERS,
)
route_order = resp.json()
route_id = route_order["route_id"]
print(f"Route order placed: {route_id}")

Example response:

{
  "route_id": "rte_9qHf3kDsEmV2",
  "link_id": "lnk_4fPq7rHsKzM1",
  "status": "executing",
  "side": "buy",
  "total_size": 5000,
  "legs": [
    {
      "venue": "polymarket",
      "order_id": "ord_2xKj9mQpLvT4",
      "size": 3200,
      "status": "open"
    },
    {
      "venue": "kalshi",
      "order_id": "ord_5nRa1bWcXzY8",
      "size": 1800,
      "status": "open"
    }
  ],
  "created_at": "2025-01-15T14:23:05Z"
}

The max_slippage field (expressed as a decimal, e.g. 0.005 = 0.5%) protects you from adverse fills if prices move between quote and execution. If either leg would exceed the slippage limit, the route order is rejected.

Step 5 — List your routed orders

Retrieve all your routed parent orders and their individual legs:

curl "https://execution.kairos.trade/orders/routes" \
  -H "X-Client-Id: $KAIROS_CLIENT_ID" \
  -H "X-Api-Key: $KAIROS_API_KEY" \
  -H "X-Api-Secret: $KAIROS_API_SECRET"

resp = httpx.get(
    "https://execution.kairos.trade/orders/routes",
    headers=API_HEADERS,
)
routes = resp.json()["routes"]
for r in routes:
    print(r["route_id"], r["status"], r["total_size"])

Step 6 — Close a routed position

To unwind your cross-venue position, call POST /orders/route-close. Kairos submits sell orders across both legs simultaneously, mirroring the same split logic used on entry.

curl -X POST "https://execution.kairos.trade/orders/route-close" \
  -H "X-Client-Id: $KAIROS_CLIENT_ID" \
  -H "X-Api-Key: $KAIROS_API_KEY" \
  -H "X-Api-Secret: $KAIROS_API_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "route_id": "rte_9qHf3kDsEmV2",
    "size": 5000
  }'

resp = httpx.post(
    "https://execution.kairos.trade/orders/route-close",
    json={
        "route_id": "rte_9qHf3kDsEmV2",
        "size": 5000,
    },
    headers=API_HEADERS,
)
print(resp.json())

Example response:

{
  "route_id": "rte_9qHf3kDsEmV2",
  "close_route_id": "rte_1mKd4jFpNwZ6",
  "status": "executing",
  "legs": [
    {
      "venue": "polymarket",
      "order_id": "ord_8hKp2qNvLzR5",
      "size": 3200,
      "status": "open"
    },
    {
      "venue": "kalshi",
      "order_id": "ord_6mJe1wBxCyT3",
      "size": 1800,
      "status": "open"
    }
  ]
}

Full workflow at a glance

import httpx

BASE = "https://execution.kairos.trade"
HEADERS = {**API_HEADERS, "Content-Type": "application/json"}

# 1. Create market link
link = httpx.post(f"{BASE}/orders/market-links", json={
    "polymarket_market_id": "0xabc123",
    "kalshi_market_id": "FED-25JAN-T0.5",
}, headers=HEADERS).json()
link_id = link["link_id"]

# 2. Get quote
quote = httpx.get(f"{BASE}/orders/route-quote", params={
    "link_id": link_id, "side": "buy", "size": 5000,
}, headers=HEADERS).json()
print(f"Blended price: {quote['blended_avg_price']}")

# 3. Execute
route = httpx.post(f"{BASE}/orders/route-buy", json={
    "link_id": link_id, "side": "buy", "size": 5000, "max_slippage": 0.005,
}, headers=HEADERS).json()
route_id = route["route_id"]

# 4. Later: close position
close = httpx.post(f"{BASE}/orders/route-close", json={
    "route_id": route_id, "size": 5000,
}, headers=HEADERS).json()
print(f"Close route: {close['close_route_id']}")

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Route Orders Across Venues with Kairos Cross-Venue Routing

How cross-venue routing works

Step 1 — Create a market link

Step 2 — Get a route quote

Step 3 — Check the fee model

Step 4 — Execute the route

Step 5 — List your routed orders

Step 6 — Close a routed position

Full workflow at a glance

Trading

Combos & Parlays

​How cross-venue routing works

​Step 1 — Create a market link

​Step 2 — Get a route quote

​Step 3 — Check the fee model

​Step 4 — Execute the route

​Step 5 — List your routed orders

​Step 6 — Close a routed position

​Full workflow at a glance

Trading

Combos & Parlays

How cross-venue routing works

Step 1 — Create a market link

Step 2 — Get a route quote

Step 3 — Check the fee model

Step 4 — Execute the route

Step 5 — List your routed orders

Step 6 — Close a routed position

Full workflow at a glance