> ## Documentation Index > Fetch the complete documentation index at: https://waffo.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Validate before starting a payment > Completes the check a pay method requires before its payment sheet can open. Apple Pay is the only one today: acquiring verifies the merchant domain and forwards the validation to Payment, which holds the Apple certificate and exchanges it for a merchant session. ## OpenAPI ````yaml /api-reference/openapi.json post /web/v1/session/validate openapi: 3.1.0 info: title: acquiring-order description: 接口文档 termsOfService: https://www.waffo.com version: 1.0.0 servers: - url: https://waffo.com description: Sandbox API (auto-signed via waffo.com signing proxy) security: [] tags: - name: Subscription inquiry description: Subscription inquiry api description - name: Subscription manage description: > This API allows the merchant to request a subscription management URL from Waffo Waffo will generate a subscription management URL which merchant can redirect user to this URL for managing subscription details (e.g. view subscription detail and cancel subscription). This management URL has a fixed expiration time (e.g., 1 day). - name: Subscription change inquiry description: > This API allows merchants to query the status of a subscription change (upgrade/downgrade) request. 此接口允许商户查询订阅升降级请求的状态。 - name: Subscription resume description: > Revoke a scheduled cancellation before it takes effect, so that the subscription keeps renewing. The next billing date stays unchanged. - name: Subscription update description: ' Subscription update api description' - name: Payment session update description: Payment session update api description - name: Order inquiry description: Order inquiry api description - name: Payout inquiry description: Payout inquiry api description - name: Order create description: ' Order create api description' - name: Pay Method Config Inquiry description: Pay Method Config Inquiry api description - name: Payment session create description: Payment session create api description - name: Order cancel description: Order cancel api description - name: Order capture description: Order capture api description - name: Subscription session create description: Subscription session create api description - name: Chargeback list description: Chargeback list api description - name: Payout create description: Payout create api description - name: Subscription session update description: Subscription session update api description - name: Payment session confirm description: Payment session confirm api description - name: Payment session validate description: Payment session validate api description - name: Payment session info description: Payment session info api description - name: Chargeback file download description: Chargeback file download api description - name: Subscription change description: > This API allows merchants to upgrade or downgrade a user's subscription plan. The change request will create a new subscription based on the original subscription, applying any remaining amount from the original subscription. 此接口允许商户升级或降级用户的订阅计划。升降级请求将基于原订阅创建新订阅，并将原订阅的剩余金额应用到新订阅中。 - name: Chargeback accept description: Chargeback accept api description - name: Chargeback file upload description: Chargeback file upload api description - name: Chargeback update description: Chargeback update api description - name: Wallet inquiry description: Wallet inquiry api description - name: Order refund description: Order refund api description - name: Refund inquiry description: Refund inquiry api description - name: Subscription cancel description: > Cancel an active subscription when the merchant no longer wishes to continue the recurring billing cycle. This endpoint can only be invoked when the subscription status is active - name: Merchant config inquiry description: Merchant config inquiry api description - name: Chargeback inquiry description: Chargeback inquiry api description - name: Subscription create description: Subscription create api description - name: Reported Fraud list description: Reported Fraud list api description paths: /web/v1/session/validate: post: tags: - Payment session validate summary: Validate before starting a payment description: >- Completes the check a pay method requires before its payment sheet can open. Apple Pay is the only one today: acquiring verifies the merchant domain and forwards the validation to Payment, which holds the Apple certificate and exchanges it for a merchant session. operationId: sessionValidate parameters: - name: x-sign-verified-mid in: header required: false schema: type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/SessionValidateRequest' required: true responses: '200': description: OK content: '*/*': schema: $ref: '#/components/schemas/ResponseString' components: schemas: SessionValidateRequest: type: object properties: sessionId: type: string description: Payment session id returned by the session create api. minLength: 1 payMethodType: type: string description: >- Pay method type to validate. Only APPLEPAY needs pre-payment validation for now. minLength: 1 validationUrl: type: string description: Validation url handed out by Apple Pay on the shopper browser. minLength: 1 merchantDomain: type: string description: >- Domain of the merchant page showing the Apple Pay button; it must be registered for this merchant. minLength: 1 required: - merchantDomain - payMethodType - sessionId - validationUrl ResponseString: type: object description: response data properties: code: type: string example: 0 msg: type: string example: success data: type: string ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.