Polymarket Place Bet

Place a bet (order) on Polymarket prediction markets. Supports BUY/SELL orders with GTC, FOK, or FAK order types. Flexible pricing modes: market, limit, or copy from variables. Ideal for: automated trading strategies, event-based betting, portfolio diversification, prediction market arbitrage.

Catalog action EVM Onchain wallet send

This action can require a wallet connector, gas, token movement, or an external side effect. Test with simulation or a controlled amount before using it in a live workflow.

At a Glance

Field	Value
Action ID	`polymarket-place-bet`
Category	EVM Onchain
Connector	`wallet`
Requires gas	No
Funds movement	`send`
Tags	`polymarket`, `trading`, `defi`, `write`

Payload Schema

Field	Type	Required	Description
`mode`	`string`	No	Mode of operation. 'manual' for selecting a specific market/outcome, 'copy' for copying trades from a trigger with all fields from variables.
`marketUrl`	`string`	No	Polymarket event URL (e.g., https://polymarket.com/event/bitcoin-up-or-down-january-14-2am-et\). When provided, the action will fetch market data and use the specified outcome to determine the token ID.
`outcome`	`string`	No	The outcome to bet on (e.g., "Up", "Down", "Yes", "No"). Required when using marketUrl. Must match one of the available outcomes in the market.
`tokenId`	`string`	No	The CLOB token ID (numeric string) representing the specific outcome to bet on. Alternative to marketUrl+outcome — provide either tokenId OR marketUrl+outcome.
`groupOutcome`	`string`	No	For multi-market events: the selected sub-market question text. Used during execution to disambiguate between sub-markets when resolving tokenId from marketUrl+outcome (e.g., grouped binary events where all outcomes are Yes/No).
`tokenIdVariable`	`string`	No	Variable reference for the token ID in copy mode (e.g., {{root.result.trade.tokenId}}). The value will be resolved at runtime.
`sideVariable`	`string`	No	Variable reference for the side (BUY/SELL) in copy mode (e.g., {{root.result.trade.side}}). The value will be resolved at runtime.
`side`	`string`	No	BUY to bet on an outcome, SELL to bet against or exit a position.
`amountMode`	`string`	No	How to determine the bet amount. 'fixed' uses a static value, 'proportional' uses a variable with multiplier.
`fixedAmount`	`string`	No	Fixed bet amount in pUSD smallest units (6 decimals). e.g. "10000000" = $10. Minimum: $1 for market orders, $5 for limit orders.
`dynamicAmount`	`string \| number`	No	Variable reference or resolved value for the amount when amountMode is 'proportional'.
`multiplier`	`number`	No	Multiplier applied to dynamicAmount amount (e.g., 0.5 for half, 2 for double).
`minAmount`	`number`	No	Minimum bet amount when using copy mode. Final amount will be clamped to this floor.
`maxAmount`	`number`	No	Maximum bet amount when using copy mode. Final amount will be clamped to this ceiling.
`priceMode`	`string`	No	How to determine the price. 'market' uses current market price, 'limit' uses a fixed price, 'copy' uses a variable.
`price`	`number`	No	Price per share between 0.01 and 0.99. Maps from limitPrice in limit mode.
`limitPrice`	`number`	No	Limit price per share (used when priceMode is 'limit'). Represents probability between 0.01 and 0.99.
`copyPriceVariable`	`string \| number`	No	Variable reference or resolved value for the price when priceMode is 'copy'.
`orderType`	`string`	No	Order type: GTC (Good Till Cancelled), GTD (Good Till Date — requires expiration), FOK (Fill Or Kill), FAK (Fill And Kill). Default is FAK for market orders.
`expiration`	`string`	No	Unix timestamp for order expiration. Required when orderType is 'GTD'. The order will be automatically cancelled after this time.
`postOnly`	`boolean`	No	If true, the limit order will only be placed as a maker order (sits on the book). If it would immediately match, the order is rejected instead of filling as a taker. Only valid for GTC/GTD order types. Maker orders have zero fees.
`metadata`	`string`	No	Optional bytes32 metadata tag for the order. Can be used for strategy tagging, workflow attribution, or downstream analytics.

Result Schema

Field	Type	Required	Description
`status`	`string`	Yes	Status of the bet placement operation. 'filled'/'matched' indicates immediate fill for market orders.
`orderId`	`string`	No	The unique identifier for the placed order
`tokenId`	`string`	No	The token ID that was bet on
`side`	`string`	No	The side of the order
`price`	`number`	No	The price per share
`size`	`number`	No	The size of the order in shares. Always present — use this instead of order-type-specific fields (sizeMatched, takingAmount) in downstream workflow nodes.
`filledSize`	`number`	No	Unified field: amount of the order that was filled (shares). Always present — works for both market and limit orders. Prefer over sizeMatched/takingAmount.
`orderType`	`string`	No	The type of order placed (GTC, GTD, FAK, FOK)
`createdAt`	`string`	No	Timestamp when the order was created
`transactionHash`	`string`	No	On-chain transaction hash for market orders that settled immediately
`tradeIds`	`array`	No	Array of trade IDs for matched/filled orders
`takingAmount`	`number`	No	Raw API field for market orders ONLY (FAK/FOK): number of shares received. NOT present for limit orders — use filledSize instead.
`makingAmount`	`number`	No	Raw API field for market orders ONLY (FAK/FOK): USDC amount spent. NOT present for limit orders — use size instead.
`sizeMatched`	`number`	No	Raw API field for limit orders ONLY (GTC): number of shares matched. NOT present for market orders — use filledSize instead.
`amountSpent`	`number`	No	Unified field: actual USDC amount spent on this order. Always present — works for both market and limit orders. For BUY orders: equals makingAmount (market) or filledSize × price (limit). For SELL orders: 0 (sells are exits, not outflow). Use this for budget tracking instead of the trigger's trade.amount.
`question`	`string`	No	The market question (e.g. 'Will Bitcoin reach $100K?'). Populated when resolved from marketUrl.
`message`	`string`	No	Optional message with additional context about the order result

Examples

json
{  "type": "polymarket-place-bet",  "payload": {    "mode": "manual",    "marketUrl": "https://example.com/webhook",    "outcome": "example-outcome",    "tokenId": "1",    "groupOutcome": "example-groupOutcome"  },  "children": [],  "connector": {    "type": "wallet",    "id": "conn_wallet"  }}

bash
curl -X POST "https://api.b3os.org/v1/actions/polymarket-place-bet/test" \  -H "Authorization: Bearer YOUR_API_KEY" \  -H "Content-Type: application/json" \  -d '{  "inputs": {    "mode": "manual",    "marketUrl": "https://example.com/webhook",    "outcome": "example-outcome",    "tokenId": "1",    "groupOutcome": "example-groupOutcome"  }}'

Payload fields can use workflow expressions such as {{$trigger.body.amount}}, {{$nodes.fetch.result.price}}, and {{$props.asset}} when the value should come from a trigger, prior node, or reusable workflow prop.

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