> ## Documentation Index > Fetch the complete documentation index at: https://dexbuilder.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Estimate deposit fees > Estimate the fees for a user's onchain deposit. Estimate the fees for a user's onchain deposit. > [!NOTE] > > Use a Broker API Key and pass the target user's wallet in X-User-Wallet-Address. The gateway checks that the wallet belongs to your Broker. See [Broker API Key and signing](https://dexbuilder.mintlify.site/en/api-reference/common/broker-authentication.md). ## Usage notes * The request `address` must be the target user's bound wallet. `lz_fee` is a USDT decimal string; convert it to an integer with six decimal places before calling [Get deposit signing data](https://dexbuilder.mintlify.site/en/api-reference/dexbuilder/deposit-sign-data.md), for example `0.5` becomes `500000`. Pass `native_fee` unchanged as an integer in the chain's smallest native unit. * `fee_source=0` means a real-time quote; `fee_source=1` means a fallback quote. ## OpenAPI ````yaml openapi/dexbuilder-en.yaml POST /api/v4/dexbuilder/deposit/fee openapi: 3.0.3 info: title: DexBuilder Platform Broker API version: 1.0.0 description: >- DexBuilder Platform Broker API for asset configuration, user queries, deposits, and withdrawals. See the shared gateway documentation for authentication and wallet verification. servers: - url: https://api.dexbuilder.com security: [] paths: /api/v4/dexbuilder/deposit/fee: post: tags: - Deposit summary: Estimate deposit fees operationId: estimateDexBuilderDepositFee parameters: - $ref: '#/components/parameters/SubUserWalletAddr' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/DepositRequest' responses: '200': description: Query successful content: application/json: schema: $ref: '#/components/schemas/EnvelopeDepositFee' '400': $ref: '#/components/responses/OpenAPIBadRequest' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '401': $ref: '#/components/responses/GatewayUnauthorized' '403': $ref: '#/components/responses/ProjectAccessDenied' security: - BrokerAPIKey: [] Timestamp: [] Signature: [] components: parameters: SubUserWalletAddr: name: X-User-Wallet-Address in: header required: true description: >- Target user's wallet address. The gateway verifies that the user belongs to the current Broker. schema: type: string schemas: DepositRequest: type: object required: - address - chain - token_address - token_amount - token_symbol properties: address: type: string description: Bound wallet initiating the deposit; EVM 0x hex or Solana base58 chain: $ref: '#/components/schemas/OpenAPIChainId' token_address: type: string description: >- Token contract; use the chain's designated zero address for a native token token_amount: type: string description: Deposit amount as a decimal string token_symbol: type: string description: Token symbol, such as USDT EnvelopeDepositFee: allOf: - $ref: '#/components/schemas/EnvelopeBase' - type: object properties: data: $ref: '#/components/schemas/PerpDepositFeeResponse' ErrorEnvelope: allOf: - $ref: '#/components/schemas/EnvelopeBase' - type: object required: - label properties: label: type: string description: Stable machine-readable error label data: nullable: true description: Usually null on error OpenAPIChainId: type: string enum: - base - bsc - ethereum - solana - arbitrum description: 'Network identifier: base, bsc, ethereum, solana, or arbitrum.' example: ethereum EnvelopeBase: type: object properties: code: type: integer example: 0 description: Business code; 0 indicates success message: type: string example: success description: Human-readable message; success responses use success reason: type: string description: Error reason identifier; usually empty on success trace_id: type: string description: Trace ID to provide when requesting support PerpDepositFeeResponse: type: object properties: deposit_fee: type: string description: Platform deposit fee as a USDT decimal string lz_fee: type: string description: >- LayerZero cross-chain fee as a USDT decimal string; convert to int64 for sign_data native_fee: type: integer format: int64 description: >- Fee in the chain's native token, as an integer in its smallest unit, such as wei fee_source: type: integer description: 'Fee source: 0 means a real-time quote; 1 means a fallback quote.' responses: OpenAPIBadRequest: description: 'Invalid request: parameters, body, user identity, or business validation' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' examples: invalidArgument: summary: Invalid parameter value: label: INVALID_ARGUMENT message: invalid argument userNotFound: summary: User not found value: label: USER_NOT_FOUND message: User not found missingHeader: summary: Missing required header value: label: MISSING_REQUIRED_HEADER message: invalid headers GatewayUnauthorized: description: Invalid Broker API Key, signature, or timestamp content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' examples: invalidKey: summary: Invalid API Key value: label: INVALID_KEY message: Invalid key provided code: 401 trace_id: abc123 invalidSignature: summary: Invalid signature value: label: INVALID_SIGNATURE message: Invalid signature code: 401 trace_id: abc123 ProjectAccessDenied: description: Project not bound, or Broker and API Key do not match content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' example: code: 40300801 reason: P_DEX_BUILDER_IN_PROJECT_ACCESS_DENIED label: PROJECT_ACCESS_DENIED message: project access denied data: null securitySchemes: BrokerAPIKey: type: apiKey in: header name: KEY description: Broker API Key Timestamp: type: apiKey in: header name: Timestamp description: Unix timestamp in seconds Signature: type: apiKey in: header name: SIGN description: Hexadecimal HMAC-SHA512 signature generated with the Broker Secret Key ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.