Kairos Platform Fee
Your platform fee uses the maker or taker schedule from the fee tier that applies to you at fill time. A tier can use a flat rate:notional = fill quantity × fill price. Maker and taker carry separate
rates, so a resting limit order and a marketable order on the same market can
be charged differently.
A curve tier instead stores ordered { price, feeBps } control points for each
side. Kairos linearly interpolates the effective basis-point rate at the fill’s
actual share price, then applies that rate to notional. Curves cover the complete
price range from 0 through 1; the makerFeeBps and takerFeeBps fields on a
curve tier expose its peak rates for backwards-compatible displays. Read
feeModel, makerFeeCurve, and takerFeeCurve to price the full schedule.
A parabolic tier stores an edge rate and a center rate for each side. For a fill
price p between 0 and 1, Kairos evaluates the exact symmetric schedule:
p = 0 and p = 1; the configured center
rate applies at p = 0.50. Read makerFeeEdgeBps, makerFeeCenterBps,
takerFeeEdgeBps, and takerFeeCenterBps when feeModel is parabolic.
How volume tiers apply
Your rolling 7-day and 30-day matched volume determines your position on the volume ladder. Tier changes take effect on the next fill, and volume tiers are recomputed as your rolling volume changes.Live fee schedule
Rendered from the live
fees.getFeeTiers configuration. Last schedule update: 2026-09-02T03:28:36Z. Rates are configuration, not a fixed schedule — the fee quote shown before an order is authoritative.Volume ladder
Gas sponsorship for a tier is typical, not a billing guarantee — availability depends on your wallet and chain integration. See the glossary.
Kairos Starter
- 7-day volume — $0
- 30-day volume — $0
- Network gas — Sponsored
- Maker rate —
0 + 4 × (0 − 0) × p × (1 − p) bps - Taker rate —
10 + 4 × (50 − 10) × p × (1 − p) bps
Kairos Bronze
- 7-day volume — $0
- 30-day volume — $50,000
- Network gas — Sponsored
- Maker rate —
0 + 4 × (0 − 0) × p × (1 − p) bps - Taker rate —
9 + 4 × (40 − 9) × p × (1 − p) bps
Kairos Silver
- 7-day volume — $0
- 30-day volume — $99,900
- Network gas — Sponsored
- Maker rate —
0 + 4 × (0 − 0) × p × (1 − p) bps - Taker rate —
8 + 4 × (30 − 8) × p × (1 − p) bps
Kairos Gold
- 7-day volume — $0
- 30-day volume — $1,000,000
- Network gas — Sponsored
- Maker rate —
0 + 4 × (0 − 0) × p × (1 − p) bps - Taker rate —
5 + 4 × (25 − 5) × p × (1 − p) bps
Exchange Fees
Venue fees are charged by the exchange, not by Kairos, and are on top of the platform fee. Polymarket and Predict.fun charge takers only — a resting maker order pays no exchange fee there. Kalshi is the exception.Polymarket
p is the share price and rate is the market’s category fee curve. The fee
peaks at p = 0.50 and tapers toward both extremes, and the result is rounded
to five decimal places.
Markets with fees disabled charge nothing regardless of category. These rates
mirror Polymarket’s published schedule and can change on their side.
Predict.fun
feeRateBps is per market and read from live market metadata. When it cannot
be resolved, the quote falls back to a 200 bps (2%) base and flags itself as an
estimate. Like Polymarket’s curve, the fee peaks at p = 0.50.
Kalshi
scale depends on the market’s series ticker — the part before the first
-. Unknown series fall back to Standard.
On the non-standard series the inversion bites: the maker pays the higher scale. Resting an order there is the expensive side, not the cheap one.
Kalshi fee quotes are estimates. Kalshi does not expose a fee API, so Kairos maintains this schedule by hand from Kalshi’s published table. Confirm against Kalshi’s published schedule for anything rate-sensitive.
Fee Quotes
GET /orders/fee-quote prices a hypothetical order against the live book and
returns the platform fee, the exchange fee, the venue reserve, the total fee,
and the all-in cost — see Fee Quote. Fee quotes
are supported for kalshi, polymarket, and predictfun.
Quotes are marked as estimates: they price off a point-in-time book, and a
market order’s realised average price (and therefore its fee) depends on what
the book looks like at execution.
For a live stream of quotes as you size an order, subscribe to
subscribe_fee_quote on the order-execution socket — see
Fee Quote WebSocket.
Network Costs
Beyond exchange fees, on-chain venues can carry network costs and collateral conversion steps that are not Kairos platform fees.The fee quote’s total cost covers the platform and exchange fees only — it
does not include network or conversion costs.