Polymarket vs Kalshi

How the two prediction-market venues differ in Scalar Field: chat discovery, scalarlib data functions, venue.* / strategy.* trading, funding, and settlement. Both are first-class venues. Chat writes Python in execute_code, screens markets, then trades with venue.trade(...). The loop is the same; the APIs, symbols, cash, and fill models are not.

Quick contrast

	Polymarket	Kalshi
Regulator / structure	On-chain CLOB (Polygon)	CFTC-regulated exchange
Chat dataset lookup	`lookupDocumentation("PolymarketData")`	`lookupDocumentation("KalshiData")`
Screen	`screenPolymarkets()`	`screenKalshiMarkets()`
Catalog	Always Postgres FTS (`POST /api/v1/db/polymarket/screen`)	Live Kalshi APIs (`POST /api/v1/db/kalshi/screen` → search or GET /markets)
Trade handle	Outcome `token_id` from `token_ids` list	`symbol` (YES) or `symbol_no` (NO)
Outcomes	Binary or multi-outcome	Binary YES / NO only
`venue.trade` account	`POLYMARKET` or `POLYMARKET_PAPER`	`KALSHI` (live only)
Cash	PUSD on `WALLET_POL` (live); virtual USDC (paper)	USD on the user’s Kalshi account
Connect	Managed Polygon wallet	User pastes API Key ID + RSA private key
Deposits / withdrawals	Via Scalar wallet / `deposit_request`	At Kalshi only — we never move cash
Paper	Yes (`POLYMARKET_PAPER`)	No
Settlement	Explicit `venue.trade("redeem", ...)` after resolution	Automatic; history `category: "settlement"`
Default market slippage	500 bps (5%)	50 bps (0.5%)
Hours	24/7	Near-24/7; pause Thu 03:00–05:00 ET
Stops	No	No
Resting limits	Yes (GTC)	Yes (GTC); market = synthesized IOC

Chat

Neither venue has a built-in market list in the prompt. The agent must look up docs, then call a screener.

	Polymarket	Kalshi
Lookup name	`PolymarketData`	`KalshiData`
What the page teaches	Full `screenPolymarkets` params, columns, OHLCV, trades, wallets, positions, profiles	Full `screenKalshiMarkets` params, columns, events, order book, candles, public tape
Trading docs	`VenueAndStrategy` — `token_ids` into `venue.trade(..., account="POLYMARKET")`	`VenueAndStrategy` — `symbol` / `symbol_no` into `venue.trade(..., account="KALSHI")`
Typical search	`screenPolymarkets(query="bitcoin", closed=False)`	`screenKalshiMarkets(query="bitcoin", closed=False)`

Unified helper (both catalogs): searchPredictionMarkets(query, venue="polymarket"|"kalshi"). Event tags apply to Polymarket only. When speaking to the user about Kalshi, describe YES vs NO in plain language. Do not mention internal ticker encodings.

Market discovery (screeners)

Shared

query, closed, min_volume, min_price / max_price (0–1), start_date / end_date (YYYY-MM-DD), sort_by (volume or created_at), limit, offset
No Kalshi/Polymarket login required

`screenPolymarkets` only

Param	Role
`market_ids`	Bulk lookup by Polymarket market id
`event_tags` / `exclude_event_tags`	Category tags (`sports`, `politics`, …)
`start_date` / `end_date`	Market lifecycle: `market_start_date >= start_date`, `market_end_date <= end_date`
Default `limit`	50

Returns (among others): market_id, market_question, market_outcomes, market_outcome_prices, token_ids (list, one CLOB token per outcome), winning_outcome_index, market_accepting_orders, event_title. closed=True is not the same as resolved. Use winning_outcome_index (set only when settled).

`screenKalshiMarkets` only

Param	Role
`tickers`	Bulk lookup by market ticker
`event_ticker` / `series_ticker`	Kalshi event / series
`status`	Query filter: `"open"` (default; `None` is the same as omit), `"closed"`, `"settled"`, `"unopened"`, `"paused"`, or aliases `"active"` / `"finalized"`. Other values raise `ValueError`. Ignored when `closed` is set.
`start_date` / `end_date`	Expiration window on `close_time` (`YYYY-MM-DD`, New York calendar days). Not a start/end pair — Kalshi’s lifecycle date is when the contract expires.
`min_close_ts` / `max_close_ts`	Same expiration window as Unix seconds
Default `limit`	100

Every row also carries close_time (expiration) and created_time (when listed). Catalog tables additionally store open_time, updated_time, and settled_time; those are not returned by the screener today. Returns (among others): ticker, title, symbol (YES trade handle), symbol_no (NO trade handle), yes_bid / yes_ask / no_bid / no_ask, last_price, volume, open_interest, close_time, created_time, price_ranges, event_title. With query, results come from Kalshi’s /v1/search/series (relevance-ranked, one page). Without query, from GET /markets (one page; volume sort is within that page).

`screenKalshiEvents`

Kalshi-only. Lists events (event_ticker, title, category, status, close_time), optionally with nested markets. Polymarket folds event fields into screenPolymarkets (event_id, event_title, event_slug). Event status query values are "open", "closed", "settled", or omit/None for any. Other values, including "active" and "finalized", raise ValueError before the request. The filter matches events that have at least one child market in that state. Event-row status is often null.

Data functions

Market data is public on both. Polymarket has a larger analytics surface because trades and positions are on-chain.

Capability	Polymarket	Kalshi
Screen markets	`screenPolymarkets`	`screenKalshiMarkets`
Screen events	(via market row)	`screenKalshiEvents`
OHLC / OHLCV	`getPolymarketOHLCV(token_ids, start, end, timeframe)` — `day`, `hour`, `5min`, `15min`, `30min`	`getKalshiCandles(ticker, start, end, period_interval)` — 1, 60, or 1440 minutes only
Live book	`getPolymarketPriceAndBook` / `getLatestSnapshot(token_id)` — full CLOB bids and asks	`getKalshiOrderbook` / `getLatestSnapshot(symbol)` — bids only per leg; ask = `1 −` opposite best bid
Public trades	`getPolymarketTrades` — filter by token, wallet, market, side, size, USDC value, time	`getKalshiTrades(ticker)` — public tape (live then historical) with `is_complete`; no wallet filter
Resolution	Market row + on-chain resolution	`getKalshiMarket` (`result`, `settlement_ts`, `settlement_value_dollars`, `status` disputed/amended)
Wallet leaderboard	`screenPolymarketWallets`	None (no public wallet graph)
Any-wallet positions	`getPolymarketPositions(wallet=...)`	None — use `venue.positions(account="KALSHI")` for the connected user
Trader profile	`getPolymarketProfile(wallet)`	None
`getLatestSnapshot`	`last`, `bid`, `ask`, full `bids`/`asks`; volume N/A	`last` (mid), `bid`, `ask`, YES or NO book; volume N/A

Kalshi candles try /series/{series}/markets/{ticker}/candlesticks first, then GET /historical/markets/{ticker}/candlesticks for archived settled markets.

Trading (`venue.*`)

Same entry points: venue.account, venue.positions, venue.balances, venue.history, venue.trade, venue.cancel, strategy.execute / strategy.place_limit.

Symbols

# Polymarket — one token_id per outcome (Yes, No, or a named outcome)
token_id = screenPolymarkets(query="bitcoin", closed=False).iloc[0]["token_ids"][0]
venue.trade("buy", token_id, 100, account="POLYMARKET")

# Kalshi — separate handles for YES and NO
row = screenKalshiMarkets(query="bitcoin", closed=False).iloc[0]
venue.trade("buy", row["symbol"], 10, account="KALSHI")       # YES
venue.trade("buy", row["symbol_no"], 5, account="KALSHI")     # NO

Order types and fills

	Polymarket	Kalshi
Market	Walks the live CLOB; fails `EXCESSIVE_SLIPPAGE` if worst fill > cap	No native market type. Synthesizes a marketable limit, snaps to `price_ranges`, submits IOC. Unfilled remainder is `PARTIALLY_FILLED`, not left resting
Limit	Resting GTC; tick grid (often 0.001); qty may be reduced so `qty × price` is whole cents	Resting GTC; must sit on `price_ranges`; off-grid prices rejected
Stop / stop-limit	Not supported	Not supported
Default slippage	500 bps	50 bps
Qty	Fractional, typically 2 decimals; `ORDER_BELOW_MINIMUM` if too small (often ≥ ~$1 notional)	Contracts, min 0.01, truncated (`ROUND_DOWN`) to 2 dp; `0.001` → 0 → rejected
Sync	Live CLOB + paper simulator block until fill or reject	Place path is synchronous IOC/GTC submit
Paper	`POLYMARKET_PAPER` — live book, real taker fees, virtual USDC, auto-provisioned	None

During the Thursday ET pause, placement fails (TRADING_PAUSED); cancels still work. Kalshi limit TIF is hardwired to GTC (not caller-selectable); market orders are synthesized IOC.

`venue.account` / cash

	Polymarket live	Polymarket paper	Kalshi
Where cash lives	`WALLET_POL` (PUSD) — exchange account is positions-only	Virtual USDC on the paper account	USD on the Kalshi account (`cash`, `portfolio_value`). `buying_power` is omitted — Kalshi’s balance API has no such field; use `cash`. Resting limits may not reduce `cash`.
`venue.balances()`	Wallet tokens (PUSD / USDC.E / …)	Paper USDC	USD on-exchange
After a fill	On-chain lag — wait before re-reading positions	Immediate	REST portfolio; no chain lag
Dust on full sell	Possible tiny leftover; treat `abs(market_value) < $0.10` as closed	Same simulator rounding	Contract qty quantized to 0.01

Low Polymarket buying power → chat should emit deposit_request with venue POLYMARKET. Kalshi funding is not a Scalar deposit card — tell the user to fund at Kalshi.

History

Category	Polymarket	Kalshi
`trade`	CLOB fills	Fills
`transfer`	`WALLET_POL` on-chain	N/A (we never transfer)
`settlement`	N/A (use `redeem`)	Auto-settlement rows (winning contracts pay $1)

Kalshi live APIs drop orders/fills older than ~3 months; Scalar merges /historical/* so portfolio history is not truncated. Public getKalshiTrades / getKalshiCandles fail over to Kalshi’s historical market-data endpoints. Kalshi trade rows use complement encoding: closing YES at $0.43 can print as side=sell, outcome=NO, price=0.57, amount=0.57. Gross cash is qty × (1 − recorded_price) on that shape — amount is quoted notional, not proceeds. Full formulas: Trading on Kalshi.

Cancel / replace

Both support cancel of resting limits. Kalshi uses V2 DELETE /portfolio/events/orders/{id}. Unknown or already-cancelled Kalshi orders can fail with a raw HTTP 410 from a legacy V1 fallback — that is not CANCEL_NOT_SUPPORTED. Kalshi replace_order is cancel-and-replace (new broker id). Stops are unsupported on both.

Settlement

Polymarket. After market_end_date, the market stops accepting orders. A closed market may still be awaiting resolution (winning_outcome_index is None). Winning tokens are not paid until venue.trade("redeem", token_id, ...). Selling a resolved market fails with MARKET_RESOLVED_USE_REDEEM. redeem is Polymarket-only (REDEEM_NOT_SUPPORTED on Kalshi). Kalshi. Winning contracts pay $1 automatically. No redeem call. Settled positions show up in venue.history(category="settlement"). venue.trade on a closed/settled/finalized market fails with a ValueError (… is {status} and cannot be traded). Strategy layer may surface that as MARKET_CLOSED.

Connect and credentials

	Polymarket live	Kalshi
What the user connects	Scalar-managed Polygon wallet (`WALLET_POL`)	Their own Kalshi API Key ID + PEM private key (shown once on kalshi.com)
Storage	Wallet material	Fernet-encrypted key in `kalshi_accounts`
Disconnect	Unlinks wallet use	Deletes our copy; key stays active on Kalshi
Withdraw / transfer	Wallet transfers via Scalar	Stored key is never granted `write::transfer`
Who holds cash	User’s Scalar wallet	User’s Kalshi account — Scalar never deposits or withdraws

Paper Polymarket needs no connect.

Strategies (`strategy.*`)

	Both	Polymarket-specific	Kalshi-specific
`execute(symbol, target_qty)`	Idempotent target position; 24/7 sync fills	`symbol` = `token_id`; paper auto-funds	`symbol` = YES/NO handle from the screener; weekly pause
`place_limit`	Supported; not idempotent	Tick + whole-cent qty rules	`price_ranges` grid
`place_stop`	Rejected	—	—
Slippage arg	Optional on `execute`	Default 500 bps	Default 50 bps
Initial positions	Claim broker holdings at approval	Look up `token_id` or `symbol`	Same unified `symbol` field
Paper	`POLYMARKET_PAPER` in `SYNC_FILL_VENUES` (in-process ledger)	—	No paper venue

Fees and ticks

Polymarket: Platform fee plus taker fee; fee_bps / fee_amount (and taker fields) on the trade response when active. Limit prices usually on a 0.001 grid; live CLOB may reject off-tick (PRICE_NOT_ON_TICK).
Kalshi: Exchange fee_cost on fills (trade fee + rounding − rebate). venue.trade() may omit finalized fees (average_fee_paid only when fill_count > 0, returned as fees not fee_amount). Use venue.history for fee/cash accounting. Prices snapped to each market’s price_ranges (often 0.01). Qty min 0.01 contracts, truncated to 2 dp.

Neither venue in this integration supports Kalshi-style perpetual futures / margin.

Frontend vs chat

The Markets explorer (GET /polymarket/markets and GET /kalshi/markets) and chat do not share a UI. Both screens eventually call the same catalog functions (screenPolymarkets / screenKalshiMarkets). Chat never opens those pages; it only runs scalarlib in the notebook kernel.

What to use when

Search a topic, then trade a probability — same pattern on both; pick the venue the user named (or both via searchPredictionMarkets).
Copy a wallet / whale flow / leaderboard — Polymarket only.
OHLC finer than 1h except 1m — Polymarket (5min / 15min / 30min). Kalshi is 1m / 1h / 1d.
Practice without funding — POLYMARKET_PAPER. There is no Kalshi paper.
USD in a CFTC venue, cash already on Kalshi — KALSHI.
On-chain PUSD / Polygon wallet — POLYMARKET + WALLET_POL.
Settle a resolved position — redeem on Polymarket; wait for automatic settlement on Kalshi.

Getting Started

Trading

Trading Venues

Market Data

Usage & Pricing

Polymarket vs kalshi

Polymarket vs Kalshi

Quick contrast

Chat

Market discovery (screeners)

Shared

`screenPolymarkets` only

`screenKalshiMarkets` only

`screenKalshiEvents`

Data functions

Trading (`venue.*`)

Symbols

Order types and fills

`venue.account` / cash

History

Cancel / replace

Cancel / replace

Settlement

Connect and credentials

Strategies (`strategy.*`)

Fees and ticks

Frontend vs chat

What to use when

​Polymarket vs Kalshi

​Quick contrast

​Chat

​Market discovery (screeners)

​Shared

​screenPolymarkets only

​screenKalshiMarkets only

​screenKalshiEvents

​Data functions

​Trading (venue.*)

​Symbols

​Order types and fills

​venue.account / cash

​History

​Cancel / replace

​Cancel / replace

​Settlement

​Connect and credentials

​Strategies (strategy.*)

​Fees and ticks

​Frontend vs chat

​What to use when

​Related

Polymarket vs Kalshi

Quick contrast

Chat

Market discovery (screeners)

Shared

`screenPolymarkets` only

`screenKalshiMarkets` only

`screenKalshiEvents`

Data functions

Trading (`venue.*`)

Symbols

Order types and fills

`venue.account` / cash

History

Cancel / replace

Cancel / replace

Settlement

Connect and credentials

Strategies (`strategy.*`)

Fees and ticks

Frontend vs chat

What to use when

Related