> ## Documentation Index > Fetch the complete documentation index at: https://docs.fossapay.com/llms.txt > Use this file to discover all available pages before exploring further. # Sign a Master Wallet Transaction > Validate, simulate, sign, and broadcast a Solana transaction with the merchant master wallet The active Solana master wallet resolved from the API key must be both a required signer and the fee payer. A successful `202` response means the transaction was submitted, not finalized. ## Headers Active production API key for the merchant that owns the master wallet. Unique key for this logical signing request, up to 255 characters. Retain it with the exact serialized transaction. ## Request body Base64-encoded serialized Solana `VersionedTransaction`, up to 4,096 characters. The selected wallet must be the fee payer and a required signer. Other required signers must sign before serialization. ```bash theme={null} curl --request POST \ --url https://api-production.fossapay.com/api/v1/wallets/crypto/master/transactions/sign-and-broadcast \ --header "x-api-key: $FOSSAPAY_API_KEY" \ --header "X-Idempotency-Key: $IDEMPOTENCY_KEY" \ --header 'Content-Type: application/json' \ --data "{\"serializedTransaction\":\"$SERIALIZED_TRANSACTION\"}" ``` ## Response ```json Submitted theme={null} { "status": "success", "statusCode": 202, "message": "Solana transaction signed and submitted successfully", "data": { "requestId": "7a7de73d-92a8-4cd8-b18c-c70e6c922a66", "walletType": "master", "customerId": null, "walletId": "65028962-9369-4f62-8758-0fc9f2e35fb2", "walletAddress": "7EcJ1eB6J3ggRrGkQWsT4ZP8dkqPZ4JmW4YRwR7Qp5cY", "network": "solana", "cluster": "mainnet-beta", "feePayer": "7EcJ1eB6J3ggRrGkQWsT4ZP8dkqPZ4JmW4YRwR7Qp5cY", "status": "submitted", "providerTransactionId": "63946f15-e605-47f4-813b-ac79f1303db9", "transactionHash": "5KtPn1yXj9DmhHVQJPNfV4PfA3BC6GgZ6JDfnYMYLXLPNqqsV5RrTRVqQJ6eTdBBL9SHSknUT9v2GkA9SGscTdQH", "explorerLink": "https://explorer.solana.com/tx/5KtPn1yXj9DmhHVQJPNfV4PfA3BC6GgZ6JDfnYMYLXLPNqqsV5RrTRVqQJ6eTdBBL9SHSknUT9v2GkA9SGscTdQH", "simulation": { "unitsConsumed": 18094, "logs": ["Program MemoSq4gqABAXKb96qnH8TysNcWxMyWCqXgDLGmfcHr success"] } } } ``` ## Important behavior * FossaPay simulates before signing and broadcasting. * The wallet initiating the transaction pays the Solana network fee. * Requests are limited to 10 per minute. * Repeating the identical submitted request with the same idempotency key returns the stored result. * A failed or expired transaction must be rebuilt with a fresh blockhash and submitted with a new key. * Finality is reconciled through Solana RPC; this flow does not emit a merchant webhook. See [Solana Transaction Signing](/guides/solana-transaction-signing) for transaction construction, statuses, retries, and security controls. ## OpenAPI ````yaml POST /api/v1/wallets/crypto/master/transactions/sign-and-broadcast openapi: 3.1.0 info: title: FossaPay API description: >- FossaPay API for checkout wallets, master-wallet payouts, customer management, NGN wallets, crypto wallets, transfers, fees, banks, and webhooks. license: name: MIT version: 1.0.0 servers: - url: https://api-production.fossapay.com description: Production server security: - ApiKeyAuth: [] paths: /api/v1/wallets/crypto/master/transactions/sign-and-broadcast: post: tags: - Crypto Wallets summary: Sign and broadcast with the master Solana wallet description: >- Validates and simulates a serialized Solana versioned transaction, then signs and broadcasts it with the authenticated merchant's active master wallet. The selected wallet must be a required signer and the fee payer. A 202 response represents submission, not on-chain finality. operationId: CryptoWalletsController_signAndBroadcastMasterTransaction parameters: - name: X-Idempotency-Key in: header required: true description: >- Unique merchant-scoped key for this exact signing request. Maximum 255 characters. schema: type: string minLength: 1 maxLength: 255 requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SolanaSigningRequest' responses: '202': description: Transaction simulated, signed, and submitted content: application/json: schema: $ref: '#/components/schemas/SolanaSigningResponse' '400': description: >- Malformed or unsupported transaction, wrong fee payer, missing co-signer, or invalid idempotency header content: application/json: schema: $ref: '#/components/schemas/ApiError' '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/ApiError' '404': description: Active master Solana wallet not found content: application/json: schema: $ref: '#/components/schemas/ApiError' '409': description: Idempotency key conflict or request already processing content: application/json: schema: $ref: '#/components/schemas/ApiError' '422': description: Solana transaction simulation failed content: application/json: schema: $ref: '#/components/schemas/ApiError' '429': description: Signing rate limit exceeded content: application/json: schema: $ref: '#/components/schemas/ApiError' components: schemas: SolanaSigningRequest: type: object required: - serializedTransaction properties: serializedTransaction: type: string minLength: 1 maxLength: 4096 description: >- Base64-encoded serialized Solana VersionedTransaction. The selected FossaPay wallet must be a required signer and the fee payer; all other required signers must already have signed. example: >- AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAQAB... additionalProperties: false SolanaSigningResponse: type: object required: - status - statusCode - message - data properties: status: type: string const: success statusCode: type: integer const: 202 message: type: string data: $ref: '#/components/schemas/SolanaSigningSubmission' additionalProperties: true ApiError: type: object properties: status: oneOf: - type: string - type: boolean statusCode: type: integer message: type: string error: type: string code: type: string errors: type: object additionalProperties: true additionalProperties: true SolanaSigningSubmission: type: object required: - requestId - walletType - walletId - walletAddress - network - cluster - feePayer - status - providerTransactionId - transactionHash - explorerLink - simulation properties: requestId: type: string format: uuid walletType: type: string enum: - master - customer customerId: type: - string - 'null' format: uuid walletId: type: string format: uuid walletAddress: type: string network: type: string const: solana cluster: type: string const: mainnet-beta feePayer: type: string status: type: string const: submitted providerTransactionId: type: string transactionHash: type: string recentBlockhash: type: string explorerLink: type: string format: uri simulation: $ref: '#/components/schemas/SolanaSigningSimulation' additionalProperties: true SolanaSigningSimulation: type: object properties: unitsConsumed: type: - integer - 'null' logs: type: array items: type: string additionalProperties: true securitySchemes: ApiKeyAuth: type: apiKey in: header name: x-api-key ````