> ## Documentation Index > Fetch the complete documentation index at: https://docs.bridg.now/llms.txt > Use this file to discover all available pages before exploring further. # Build transaction > Turn a quote into the unsigned transactions a wallet signs. Pass `quoteId` to build a row other than `best`. `steps` is every transaction to sign, in order; only `main` moves the order. A deposit-address venue returns `deposit` instead of `steps`. `expectedOutAtomic` equals the `amountOutAtomic` of the row you built. Idempotent per `decisionId`. ## OpenAPI ````yaml openapi/openapi.json POST /bridge/build openapi: 3.1.0 info: title: Bridg API version: 1.0.0 description: >- Quote, build, submit and track cross-chain transfers across every venue Bridg aggregates. servers: - url: https://api.bridg.now/v1 security: [] paths: /bridge/build: post: tags: - bridge summary: Build transaction description: >- Turn a quote into the unsigned transactions a wallet signs. Pass `quoteId` to build a row other than `best`. `steps` is every transaction to sign, in order; only `main` moves the order. A deposit-address venue returns `deposit` instead of `steps`. `expectedOutAtomic` equals the `amountOutAtomic` of the row you built. Idempotent per `decisionId`. requestBody: required: true content: application/json: schema: type: object properties: decisionId: type: string pattern: >- ^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$ venue: type: string minLength: 1 maxLength: 40 quoteId: type: string minLength: 1 maxLength: 200 privacy: type: boolean default: false userIp: anyOf: - type: string format: ip - type: string format: ip required: - decisionId example: decisionId: fb0798dc-97d2-41f2-8786-ace0b1c40722 responses: '200': description: The transfer id and the unsigned steps content: application/json: schema: type: object properties: transferId: type: string venue: type: string steps: type: array items: oneOf: - type: object properties: vm: type: string enum: - evm step: type: string enum: - approve - fee - main - redeem chainId: type: integer to: type: string data: type: string value: type: string gasLimit: type: string required: - vm - step - chainId - to - data - value - type: object properties: vm: type: string enum: - svm step: type: string enum: - approve - fee - main - redeem serializedTx: type: string encoding: type: string enum: - base64 - hex version: type: string enum: - v0 - legacy setPriorityFee: type: boolean refreshBlockhash: type: boolean required: - vm - step - serializedTx - encoding - version - setPriorityFee - refreshBlockhash - type: object properties: vm: type: string enum: - deposit-address step: type: string enum: - approve - fee - main - redeem venueChainId: type: string address: type: string memo: type: string tokenAddress: type: string nullable: true exactAmountAtomic: type: string expiresAt: type: integer required: - vm - step - venueChainId - address - tokenAddress - exactAmountAtomic - expiresAt - type: object properties: vm: type: string enum: - sign step: type: string enum: - approve - fee - main - redeem scheme: type: string enum: - eip712 - eip191 - ed25519 - nep413 payload: nullable: true required: - vm - step - scheme - type: object properties: vm: type: string enum: - utxo step: type: string enum: - approve - fee - main - redeem outputs: type: array items: type: object properties: address: type: string valueSats: type: string required: - address - valueSats memo: type: string feeRateSatsPerVbyte: type: number required: - vm - step - outputs - oneOf: - type: object properties: vm: type: string enum: - tron step: type: string enum: - approve - fee - main - redeem kind: type: string enum: - call contract: type: string data: type: string callValueSun: type: string feeLimitSun: type: string nullable: true required: - vm - step - kind - contract - data - callValueSun - feeLimitSun - type: object properties: vm: type: string enum: - tron step: type: string enum: - approve - fee - main - redeem kind: type: string enum: - transfer toAddress: type: string amountSun: type: string required: - vm - step - kind - toAddress - amountSun - type: object properties: vm: type: string enum: - tron step: type: string enum: - approve - fee - main - redeem kind: type: string enum: - built raw: nullable: true required: - vm - step - kind - type: object properties: vm: type: string enum: - unsupported step: type: string enum: - main reason: type: string required: - vm - step - reason deposit: type: object properties: address: type: string amountAtomic: type: string memo: type: string deadlineMs: type: integer tokenAddress: type: string nullable: true chainKey: type: string required: - address - amountAtomic - deadlineMs - tokenAddress - chainKey expiresAt: type: integer amountInAtomic: type: string expectedOutAtomic: type: string minOutAtomic: type: string feeCapture: type: string enum: - venue-param - merged - separate-step - batch - none referralCapture: type: string nullable: true enum: - merged - batch - none - null feeBasis: type: string enum: - carved - added feeBatch: type: object properties: chainId: type: integer stepIndexes: type: array items: type: integer required: - chainId - stepIndexes requoted: type: boolean requote: type: object properties: basis: type: string enum: - netOutAtomic - amountOutAtomic - amountInAtomic originalAmount: type: string freshAmount: type: string driftBps: type: integer required: - basis - originalAmount - freshAmount - driftBps boardDrift: type: object properties: corridorKey: type: string boardAmountOutAtomic: type: string firmAmountOutAtomic: type: string driftBps: type: integer boardAgeMs: type: integer required: - corridorKey - boardAmountOutAtomic - firmAmountOutAtomic - driftBps - boardAgeMs required: - transferId - venue - steps - expiresAt - amountInAtomic - expectedOutAtomic - minOutAtomic - feeCapture - referralCapture - feeBasis - requoted example: transferId: ca0e5dee-be62-4a8d-aab9-3c8762b29281 venue: across steps: - vm: evm step: approve chainId: 8453 to: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913' data: >- 0x095ea7b300000000000000000000000028b5a0e9c621a5badaa536219b3a228c8168cf5d0000000000000000000000000000000000000000000000000000000005f51db0 value: '0' - vm: evm step: fee chainId: 8453 to: '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913' data: >- 0xa9059cbb00000000000000000000000058e602386db134b1f9b1d6d390c11a2b7b486677000000000000000000000000000000000000000000000000000000000000c350 value: '0' - vm: evm step: main chainId: 8453 to: '0x28b5a0e9C621a5BadaA536219b3a228C8168cf5d' value: '0' data: >- 0x8e0250ee0000000000000000000000000000000000000000000000000000000005f51db00000000000000000000000000000000000000000000000000000000000000005f83ed8a61fb15505c93de93dffdc5e0d7c573df3f2bc3231c35312da4af16fc2000000000000000000000000833589fcd6edb6e08f4c7c32d4f71b54bda02913caa0da1eec44e89949baa43ecd3fde9fa3b551c53f9dba7492caa875cfa5c47400000000000000000000000000000000000000000000000000000000000032c200000000000000000000000000000000000000000000000000000000000003e81dc0de02c873c0de expiresAt: 1789929586118 amountInAtomic: '99950000' expectedOutAtomic: '99937006' minOutAtomic: '99937006' feeCapture: batch referralCapture: null feeBasis: carved feeBatch: chainId: 8453 stepIndexes: - 0 - 1 - 2 permit: null relayFeePermit: null spotTransfer: null requoted: false '400': description: >- Malformed request, an unknown asset, or a signed transaction that is not what we built content: application/json: schema: type: object properties: error: type: object properties: code: type: string message: type: string details: type: object additionalProperties: nullable: true retryAfterMs: type: integer required: - code - message required: - error '404': description: No such decision or transfer, or the aggregator is switched off content: application/json: schema: type: object properties: error: type: object properties: code: type: string message: type: string details: type: object additionalProperties: nullable: true retryAfterMs: type: integer required: - code - message required: - error '409': description: >- The decision is indicative, the quote expired or drifted, the venue is ineligible, or execution is switched off content: application/json: schema: type: object properties: error: type: object properties: code: type: string message: type: string details: type: object additionalProperties: nullable: true retryAfterMs: type: integer required: - code - message required: - error '429': description: Rate limited; retry after `retryAfterMs` content: application/json: schema: type: object properties: error: type: object properties: code: type: string message: type: string details: type: object additionalProperties: nullable: true retryAfterMs: type: integer required: - code - message required: - error '502': description: The venue refused to build, or the broadcast was rejected content: application/json: schema: type: object properties: error: type: object properties: code: type: string message: type: string details: type: object additionalProperties: nullable: true retryAfterMs: type: integer required: - code - message required: - error ````