> ## Documentation Index > Fetch the complete documentation index at: https://docs.nxos.io/llms.txt > Use this file to discover all available pages before exploring further. # Fund a test balance > Simulate a crypto deposit into an account's provisioned deposit address. Credits the ledger immediately and returns a `COMPLETED` `CRYPTO_PAYIN` transaction — no real on-chain transfer is required. Use it to fund test accounts and exercise the full pay-in → balance → pay-out loop. **Sandbox only.** In production this endpoint returns `404 not_found` as if it did not exist. The asset must already be activated on the account (so a deposit address exists on `chainName`). ## OpenAPI ````yaml POST /v1/transactions/faucet openapi: 3.0.0 info: title: nxos API version: 1.0.0 contact: name: nxos url: https://nxos.io description: |- The nxos platform API provides programmatic access to accounts, balances, quotes, and trades. All endpoints require API key authentication. servers: - url: https://api.nxos.io description: Production variables: {} - url: https://api.sandbox.nxos.io description: Sandbox variables: {} security: [] tags: - name: Accounts - name: Quotes - name: Beneficiaries - name: Fiat Payouts - name: Crypto Payouts - name: Sandbox Faucet - name: Nxosnet - name: Fees - name: Funding Methods - name: Transactions - name: Organizations - name: Authorizations - name: Webhooks description: >- Register an HTTPS endpoint to receive events (organization verification and transaction status changes) instead of polling. Deliveries are signed; verify the `svix-signature` header before acting on an event. See the [Webhooks guide](https://docs.nxos.io/core-concepts/webhooks) for the delivery format, signature verification, retries, and broker behavior. Payload shapes are documented in the `…Event` models below. paths: /v1/transactions/faucet: post: tags: - Sandbox Faucet description: >- Simulate a crypto deposit into an account's provisioned deposit address. Credits the ledger immediately and returns a `COMPLETED` `CRYPTO_PAYIN` transaction — no real on-chain transfer is required. Use it to fund test accounts and exercise the full pay-in → balance → pay-out loop. **Sandbox only.** In production this endpoint returns `404 not_found` as if it did not exist. The asset must already be activated on the account (so a deposit address exists on `chainName`). operationId: Faucet_fund parameters: - $ref: '#/components/parameters/ApiKeyAuth' - $ref: '#/components/parameters/IdempotencyKey' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/FaucetRequest' responses: '200': description: The request has succeeded. content: application/json: schema: $ref: '#/components/schemas/FaucetTransaction' '400': description: The server could not understand the request due to invalid syntax. content: application/json: schema: $ref: '#/components/schemas/Error400' '401': description: Access is unauthorized. content: application/json: schema: $ref: '#/components/schemas/Error401' '404': description: The server cannot find the requested resource. content: application/json: schema: $ref: '#/components/schemas/Error404' '429': description: Client error content: application/json: schema: $ref: '#/components/schemas/Error429' '500': description: Server error content: application/json: schema: $ref: '#/components/schemas/Error500' components: parameters: ApiKeyAuth: name: Authorization in: header required: true description: 'Bearer token. Format: `Bearer `' schema: type: string IdempotencyKey: name: Idempotency-Key in: header required: false description: >- Unique key per logical operation. UUID v4 recommended. Max 255 characters. schema: type: string schemas: FaucetRequest: type: object required: - accountId - asset - amount - chainName properties: accountId: type: string description: Account to credit. asset: type: string description: Asset code to deposit (e.g. `USDC`, `USDT`). amount: allOf: - $ref: '#/components/schemas/amount' description: Deposit amount in major units (e.g. `"10000.00"`). chainName: type: string description: >- Chain the account's deposit address lives on. Sandbox chains: `ETHEREUM_SEPOLIA`, `ARBITRUM_SEPOLIA`, `BASE_SEPOLIA`, `BSC_TESTNET`, `SOLANA_DEVNET`, `TRON_NILE`. description: Request body for funding a test balance via the sandbox faucet. example: accountId: acct_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 asset: USDC amount: '10000.000000' chainName: ETHEREUM_SEPOLIA FaucetTransaction: type: object required: - object - transactionId - type - status - accountId - amount - asset - chainName - createdAt properties: object: type: string enum: - transaction description: Object type. Always `transaction`. transactionId: type: string description: Unique transaction identifier. type: type: string enum: - CRYPTO_PAYIN description: Transaction type. Always `CRYPTO_PAYIN`. status: type: string enum: - COMPLETED description: >- Transaction status. Always `COMPLETED` — the simulated deposit is credited immediately. accountId: type: string description: Credited account. amount: allOf: - $ref: '#/components/schemas/amount' description: Deposit amount in major units. asset: type: string description: Asset code. chainName: type: string description: Chain the deposit was simulated on. createdAt: allOf: - $ref: '#/components/schemas/dateTimeString' description: When the transaction was created. description: A simulated crypto deposit produced by the sandbox faucet. example: object: transaction transactionId: txn_c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6 type: CRYPTO_PAYIN status: COMPLETED accountId: acct_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 amount: '10000.000000' asset: USDC chainName: ETHEREUM_SEPOLIA createdAt: '2025-03-15T14:32:00.000Z' Error400: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorBody' description: Standard error response returned by all endpoints on failure. example: error: code: invalid_request message: The request body is malformed or missing required fields. requestId: req_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 Error401: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorBody' description: Standard error response returned by all endpoints on failure. example: error: code: missing_api_key message: No Authorization header provided. requestId: req_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 Error404: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorBody' description: Standard error response returned by all endpoints on failure. example: error: code: not_found message: The requested resource was not found. requestId: req_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 Error429: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorBody' description: Standard error response returned by all endpoints on failure. example: error: code: rate_limited message: 'Rate limit exceeded: 1000 requests per minute. Retry in 23 seconds.' requestId: req_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 Error500: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorBody' description: Standard error response returned by all endpoints on failure. example: error: code: internal_error message: An unexpected server error occurred. requestId: req_a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4 amount: type: string description: >- Monetary amount as a decimal string in major units (e.g., `"10.50"` for ten dollars and fifty cents). Amounts are always returned at the asset's native precision — for example, USDT amounts have 6 decimal places (`"10.500000"`). Clients should parse amounts as arbitrary-precision decimals, never as floating-point numbers, to avoid rounding errors. Internally, the platform stores all amounts as integer subunits and converts at the API boundary. dateTimeString: type: string description: ISO 8601 timestamp string. ErrorBody: type: object required: - code - message - requestId properties: code: allOf: - $ref: '#/components/schemas/ErrorCode' description: Machine-readable error code. message: type: string description: Human-readable error message. requestId: type: string description: Unique identifier for this request, useful for debugging. ErrorCode: type: string enum: - missing_api_key - authentication_failed - invalid_api_key - forbidden - swap_direction_not_allowed - service_not_enabled - not_found - organization_not_found - account_not_found - quote_not_found - beneficiary_not_found - transaction_not_found - funding_method_not_found - authorization_not_found - nxosnet_handle_not_found - quote_expired - quote_already_used - beneficiary_already_archived - beneficiary_not_archived - beneficiary_blocked - nxosnet_not_enabled - nxosnet_handle_taken - chain_send_failed - idempotency_key_in_use - idempotency_request_in_flight - invalid_request - insufficient_funds - validation_error - share_token_invalid - verification_import_unsupported - verification_required - rate_limited - webhooks_unavailable - internal_error description: All possible error codes returned by the API. ````