If you’re building an app on top of Predexon, you can add a partner fee to every Polymarket trade your users make. This guide explains how fees work across both venues and how to set up monetization.
How Fees Work
Polymarket
Polymarket orders have two fee components:
- Platform fee — currently 0 bps (no platform fee)
- Partner fee — configurable by you, from 10 to 500 bps (0.1% to 5%)
The total fee is platformFeeBps + partnerFeeBps. With no partner fee configured, trading is free.
How fees are deducted depends on the order type:
- Market BUY — the fee is deducted upfront. Your
amount is reduced before execution. For example, if you submit amount: "10" with a 50 bps fee, $9.95 is used for the order and $0.05 is deducted as the fee.
- All other orders (market sell, limit buy, limit sell) — the full
size is used for the order. The fee is calculated and settled after the order fills.
Predict.fun
Predict.fun charges an exchange fee that varies by market. This is applied automatically by Predict’s matching engine — you don’t need to account for it in your order parameters, and there’s no configurable partner fee for Predict.
Set Up a Partner Fee
Partner fees are configured per API key and apply to all Polymarket orders placed by that key’s users.
Step 1: Set your fee policy
import requests
HEADERS = {"x-api-key": "YOUR_API_KEY", "Content-Type": "application/json"}
policy = requests.put(
"https://trade.predexon.com/api/fees/policy/polymarket",
headers=HEADERS,
json={
"partnerFeeBps": 50, # 0.5%
"partnerTreasuryAddress": "0xAbCdEf...01" # where fees are sent
}
).json()
print(f"Total fee: {policy['totalFeeBps']} bps ({policy['totalFeeBps'] / 100}%)")
print(f"Treasury: {policy['partnerTreasuryAddress']}")
Partner fees have a minimum of 10 bps when enabled. The maximum total fee (platform + partner) is 500 bps (5%). Set partnerFeeBps to 0 to disable.
Step 2: Verify your policy
policy = requests.get(
"https://trade.predexon.com/api/fees/policy/polymarket",
headers=HEADERS
).json()
print(f"Platform fee: {policy['platformFeeBps']} bps")
print(f"Partner fee: {policy['partnerFeeBps']} bps")
print(f"Total: {policy['totalFeeBps']} bps")
print(f"Treasury: {policy['partnerTreasuryAddress']}")
partnerFeeBps: 0 and partnerTreasuryAddress: null.
Step 3: Confirm fees in order responses
Once your policy is active, every Polymarket order response includes a fee object:
{
"orderId": "0xe692...",
"status": "filled",
"fee": {
"policyApplied": true,
"feeBps": 50,
"platformFeeBps": 0,
"partnerFeeBps": 50,
"grossAmount": "10",
"netOrderAmount": "9.95",
"maxFeeReserved": "0.05"
}
}
grossAmount, netOrderAmount, and maxFeeReserved fields are only present on market BUY orders (since the fee is deducted upfront).
Remove Your Partner Fee
policy = requests.delete(
"https://trade.predexon.com/api/fees/policy/polymarket",
headers=HEADERS
).json()
print(f"Partner fee: {policy['partnerFeeBps']} bps") # 0
If two requests update the policy at the same time, one will receive a 409 Conflict. Simply retry.
Fee Comparison
| Polymarket | Predict.fun |
|---|
| Platform fee | 0 bps | N/A |
| Partner fee | 10–500 bps (configurable) | Not available |
| Exchange fee | Per Polymarket schedule | Varies by market |
| Fee API | Get / Set / Remove | N/A |
| Fee in response | fee object on orders | Not included |
Next Steps
