> ## Documentation Index > Fetch the complete documentation index at: https://docs.updown.fast/llms.txt > Use this file to discover all available pages before exploring further. # Create order > Place a limit order (`trade` key). `client_order_id` is required and idempotent: resending the same id with the same body returns the order already placed, never a second one. After a timeout or `503 EXCHANGE_UNAVAILABLE`, retry with the SAME id. ## OpenAPI ````yaml api-reference/openapi.json POST /portfolio/orders openapi: 3.1.0 info: title: updown Trade API version: 1.0.0 description: >- Public REST API. Market data needs no key; `/account` (and order entry, when it ships) takes an API key. Prices are dollar strings on the 1ยข grid, counts are contract strings, times are epoch ms. Generated from packages/protocol โ€” do not edit by hand. servers: - url: https://api.updown.fast/trade-api/v1 description: production security: [] paths: /portfolio/orders: post: summary: Create order description: >- Place a limit order (`trade` key). `client_order_id` is required and idempotent: resending the same id with the same body returns the order already placed, never a second one. After a timeout or `503 EXCHANGE_UNAVAILABLE`, retry with the SAME id. operationId: createOrder requestBody: $ref: '#/components/requestBodies/CreateOrder' responses: '201': description: The order, as the book holds it after this call. content: application/json: schema: $ref: '#/components/schemas/OrderResponse' '400': description: Invalid request (code BAD_REQUEST). content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: No API key, or one that isn't valid (code UNAUTHORIZED). content: application/json: schema: $ref: '#/components/schemas/Error' '403': description: >- The key lacks the permission, or the account can't trade yet (code FORBIDDEN). content: application/json: schema: $ref: '#/components/schemas/Error' '409': description: >- IDEMPOTENCY_CONFLICT (that id was used for a different order) or ACCOUNT_BUSY (retry in a moment). content: application/json: schema: $ref: '#/components/schemas/Error' '429': description: Rate limited (code RATE_LIMITED); wait `Retry-After` seconds. content: application/json: schema: $ref: '#/components/schemas/Error' '503': description: The book could not be read (code EXCHANGE_UNAVAILABLE); retry. content: application/json: schema: $ref: '#/components/schemas/Error' security: - apiKey: [] components: requestBodies: CreateOrder: required: true content: application/json: schema: $ref: '#/components/schemas/CreateOrderRequest' schemas: OrderResponse: type: object properties: order: type: object properties: order_id: type: string client_order_id: type: string pattern: ^[A-Za-z0-9._:-]{1,64}$ description: >- Your id for the order, unique per account. Retrying with the same id never places a second order. market_ticker: type: string pattern: ^[a-z0-9][a-z0-9-]{0,63}-\d{6}-\d{4}-\d{4}(d\d{1,2})?$ description: >- Market ticker (one window of a series), e.g. "btc-15m-261002-1400-1415". Opaque. outcome: type: string enum: - up - down action: type: string enum: - buy - sell price: type: string pattern: ^0\.(0[1-9]|[1-9]\d)$ description: 'Contract price in dollars, "0.01"โ€“"0.99" (v1: whole cents).' time_in_force: type: string enum: - good_till_canceled - immediate_or_cancel description: >- good_till_canceled: what doesn't fill rests on the book until it fills, you cancel it or the window closes. immediate_or_cancel: fills what it can now; the rest is cancelled. post_only: type: boolean status: type: string enum: - resting - executed - canceled count: type: string pattern: ^(0|[1-9]\d*)$ description: 'Contracts, as a string (v1: whole contracts).' fill_count: type: string pattern: ^(0|[1-9]\d*)$ description: 'Contracts, as a string (v1: whole contracts).' remaining_count: type: string pattern: ^(0|[1-9]\d*)$ description: 'Contracts, as a string (v1: whole contracts).' average_fill_price: type: string fees_paid: type: string created_ts_ms: type: integer minimum: 0 maximum: 9007199254740991 description: Epoch milliseconds (UTC). required: - order_id - client_order_id - market_ticker - outcome - action - price - time_in_force - post_only - status - count - fill_count - remaining_count - created_ts_ms additionalProperties: false required: - order additionalProperties: false Error: type: object properties: code: type: string enum: - BAD_REQUEST - NOT_FOUND - SERIES_NOT_FOUND - MARKET_NOT_FOUND - METHOD_NOT_ALLOWED - RATE_LIMITED - UNAUTHORIZED - FORBIDDEN - ORDER_NOT_FOUND - IDEMPOTENCY_CONFLICT - ACCOUNT_BUSY - MARKET_NOT_OPEN - INSUFFICIENT_BALANCE - LIMIT_EXCEEDED - POST_ONLY_CROSS - SELF_TRADE - TRADING_PAUSED - ORDER_REJECTED - INTERNAL_ERROR - EXCHANGE_UNAVAILABLE message: type: string details: type: string required: - code - message additionalProperties: false CreateOrderRequest: type: object properties: market_ticker: type: string pattern: ^[a-z0-9][a-z0-9-]{0,63}-\d{6}-\d{4}-\d{4}(d\d{1,2})?$ description: >- Market ticker (one window of a series), e.g. "btc-15m-261002-1400-1415". Opaque. outcome: type: string enum: - up - down action: type: string enum: - buy - sell price: type: string pattern: ^0\.(0[1-9]|[1-9]\d)$ description: 'Contract price in dollars, "0.01"โ€“"0.99" (v1: whole cents).' count: type: string pattern: ^(0|[1-9]\d*)$ description: 'Contracts, as a string (v1: whole contracts).' time_in_force: default: good_till_canceled type: string enum: - good_till_canceled - immediate_or_cancel description: >- good_till_canceled: what doesn't fill rests on the book until it fills, you cancel it or the window closes. immediate_or_cancel: fills what it can now; the rest is cancelled. post_only: default: false type: boolean client_order_id: type: string pattern: ^[A-Za-z0-9._:-]{1,64}$ description: >- Your id for the order, unique per account. Retrying with the same id never places a second order. required: - market_ticker - outcome - action - price - count - client_order_id additionalProperties: false securitySchemes: apiKey: type: http scheme: bearer description: >- An API key from your account: `Authorization: Bearer udk___`. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.