The same outcome often trades on World, Kalshi and Polymarket at once. Half the time World is within about half a cent of the best price, and nine times in ten within 1.6¢. I built a PayBox plugin so your agent pays a cent to catch the ones that aren't, before it buys.
This preview is free and needs no wallet. It asks Kalshi and Polymarket live, and uses World's price from my last snapshot (16 Oct, 11:43 UTC). Inside PayBox, your agent sends World's live price and pays 0.01 USDC.
Free preview · World price from snapshot
In PayBox: live World price, 0.01 USDC on Base
Second Opinion is a PayBox plugin. Your agent calls it right before it buys a YES on World. Each check costs one cent.
Your agent finds the market and its live YES price with PayBox's World plugin.
It calls Second Opinion's second_opinion tool with the World ticker and that price.
second_opinion({ world_ticker: "WXPRESWIN-28-GNEW", world_yes_ask: 0.1055 })
PayBox shows a 0.01 USDC approval. You approve with your passkey. The receipt comes back, and the agent buys, waits, or sets a lower price.
Before you buy Newsom YES on World, get a Second Opinion.
I matched every World outcome I could to the same outcome on Kalshi or Polymarket. Then I measured how far World's YES price sat above the cheapest one. Most of the time the gap is small.
Kalshi and Polymarket charge buyers a taker fee on top of their price. World doesn't, because its cost is already in the quote. With those fees added:
On the 49 outcomes that are 2¢ or more over before fees, a buyer pays a median of about $20 more per $100 than on the cheaper venue.
Method. World quotes come from the PayBox World plugin. Kalshi and Polymarket quotes come from their public APIs. I only compare the same outcome with the same resolution period, and I leave out the 23 pairs where Kalshi and Polymarket disagree by more than 3¢, because that usually means the rules differ. The verdict compares YES asks. The after-fees view adds Kalshi's taker fee (0.07 × p × (1 − p) per share) and Polymarket's (its category rate, 0 to 0.07, × p × (1 − p)), using World's category for Polymarket's; Kalshi's rounding up to the cent per order is left out. Snapshot 16 Oct 2026, 11:43 UTC.
Real checks from my own PayBox account, paid in USDC on Base through x402. In the last four, my agent took World's live price from PayBox's World plugin first.
| UTC | Market | Verdict | Base transaction | Check |
|---|---|---|---|---|
| 16 Oct 15:58 | Newsom YES, 2028 | STRETCHED | 0x970adb03…8b8a | Check on Base |
| 16 Oct 16:04 | Newsom YES, 2028 | STRETCHED | 0x872e1d37…4c3b | Check on Base |
| 16 Oct 16:24 | Newsom YES, 2028, live World ask | STRETCHED | 0xf46b8dc6…a6a7 | Check on Base |
| 17 Oct 07:17 | Karen Bass YES, LA mayor, live World ask | FAIR PRICE | 0xfe217631…3300 | Check on Base |
| 17 Oct 13:53 | Karen Bass YES, approved in PayBox | FAIR PRICE | 0xfdfbb39b…5a70 | Check on Base |
| 17 Oct 13:54 | Then Claude raised a $1 Karen Bass YES buy through PayBox's World plugin | ORDER RAISED | World's region check blocked it from the UK before I could sign. Nothing spent. | |
| 17 Oct 13:57 | Karen Bass YES, approved in PayBox | FAIR PRICE | 0xf926e239…4609 | Check on Base |
