Venues

Routeur covers Kalshi and global Polymarket. Their listings, prices, fees and histories are shaped differently; the API gives both the same form and keeps each venue’s own identifiers so you can act on them. This page lists the differences that matter when you read a response or place an order. You need it whenever a field’s meaning depends on which venue it came from.

Identifiers and shape

	Kalshi	Polymarket
`venue`	`kalshi`	`polymarket`
Market `id`	The market ticker: `KXFEDDECISION-26OCT-H0`	The market slug: `will-there-be-no-change-in-fed-interest-rates-after-the-october-2026-meeting-20260617190324031`
Event `id`	The event ticker: `KXFEDDECISION-26OCT`	Polymarket’s numeric event id, as a string: `606422`
Series	The ticker prefix before the first hyphen: `KXFEDDECISION`	None; economics and sports markets are recognised from their slugs and templates
Sides	A Yes and a No on every market	Two outcome tokens per market; the first is Yes, the second No, and `yes_label` and `no_label` follow that order
Market `category`	The series’ category, such as `Elections` or `Financials`	Up to four event tags joined with `·`, such as `Sports · Games · Soccer · Eredivisie`
One-winner events	The venue’s flag on the event	The event is negative-risk and every market shares one neg-risk group
Trade `outcome`	`yes` or `no`	The outcome’s label, with its `token`
Trade `id`	The venue’s trade id	A hash of the fill, since the venue has none
Block trades	Flagged by the venue	Never flagged live; archived fills of $10,000 or more are marked by size
Payout	USD	USDC

Events carry the shared category (Sports, Politics, and so on) whatever the venue; markets keep the venue’s own wording.

Prices

Every price is an ask per contract that pays $1, as a decimal string in USD. The implied chance of an outcome is the midpoint of its best Yes ask and one minus its best No ask across the venues that list it. When an outcome is listed on both venues, prices carries each venue’s asks and best_venue names the cheaper Yes.

	Kalshi	Polymarket
Crawled	Every 15 minutes	Every 30 minutes
Bids	The best bid, counted only when size rests at it	The best bid from the venue; the No bid is one minus the best Yes ask
Ask precision	Cents: `0.52`	Sub-cent: `0.989`

Quotes are recorded when the ask pair changes, on each crawl, so they arrive in bursts. Order books are recorded live from each venue’s feed at full depth for tradeable and deep markets, and polled five levels a side for the rest; see Order books.

Size

	Kalshi	Polymarket
`volume_24h_usd`	Contracts traded, at their $1 face value, as Kalshi’s own site shows it	USDC notional, as Polymarket reports it
`total_volume_usd`	Reported	Reported
`open_interest_usd`	Contracts held, at face value	Not reported; absent
`volume_source`	`venue`	`venue`, or `trades` when the venue gives no 24-hour figure and Routeur’s recorded fills are used

The liquidity grade uses the same thresholds on both venues: deep at $25,000 traded or $250,000 open interest with a round trip of 2¢ or less, tradeable at $1,000 or $25,000 with 5¢ or less. Since Polymarket reports no open interest, its markets qualify on volume alone.

Fees

	Kalshi	Polymarket
Taker fee	0.07 × p × (1 − p) per contract, rounded up to the cent, times the series’ multiplier	rate × p × (1 − p) per share on markets with fees enabled; zero on the rest
Minimum order	One whole contract	The market’s own minimum, in shares

Leads carry estimated_fee_usd from these schedules and say in issues which parts are estimated. Fees change; treat estimates as estimates.

History

	Kalshi	Polymarket
Quotes and trades	Recorded live since listing	Recorded live since listing
Before recording	Daily candles from Kalshi’s own candlestick history, hourly over the last week of busy markets, `source: venue`	Daily and hourly candles rolled up from an imported archive of probability snapshots, `source: archive`
Settled markets	Kalshi’s own archive of settled markets, read by the backfill job	Markets in the imported archive that have since settled, rechecked every six hours
Calibration price	Midpoint of the daily candle’s closing bid and ask, or the last trade	The last recorded probability of the day

Polymarket’s settled history is much smaller than Kalshi’s, which is why its calibration bands are sparse and no strategy is listed for it alone yet. See History.

Contract versions

A market’s terms can change. Each version has a rules_hash, and relations are proven against a specific version; when terms change, the market is re-read and its relations proven again. Kalshi’s terms sit in series and event rulebooks above the market; Polymarket’s resolution metadata is per market. Every version of both is kept with diffs; see Rules.

Events and markets: the shared shape.
Cross-venue pairs: which games and releases are proven the same on both venues.
Liquidity: grades and floors.
Data and limits: coverage and limits in one place.

Get started

Concepts

Agents & MCP

Webhooks

Reference

Identifiers and shape

Prices

Size

Fees

History

Contract versions

Identifiers and shape

Prices

Size

Fees

History

Contract versions

Related