> For the complete documentation index, see [llms.txt](https://docs.pay.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pay.io/api-reference/user-payment-api/create-a-payment-session.md).

# Create a Payment Session

## Create a payment session

> Creates a payment session. ON\_RAMP routes to MELD; OFF\_RAMP is accepted in the contract but returns 501 in Phase 1. Country is mandatory; custom\_wallet\_address requires the merchant's allow\_custom\_external\_wallet flag.

```json
{"openapi":"3.0.0","info":{"title":"pay.io payment gateway","version":"1.0"},"servers":[{"url":"https://gateway.stage.pay.io","variables":{}}],"paths":{"/v1/user/payments":{"post":{"callbacks":{},"description":"Creates a payment session. ON_RAMP routes to MELD; OFF_RAMP is accepted in the contract but returns 501 in Phase 1. Country is mandatory; custom_wallet_address requires the merchant's allow_custom_external_wallet flag.","operationId":"HubwalletPaymentGatewayWeb.Controller.Merchant.Default.payment_sessions","parameters":[],"requestBody":{"content":{"application/json":{"schema":{"$ref":"#/components/schemas/Payment_Session_Request"}}},"description":"Payment session attributes","required":true},"responses":{"200":{"content":{"application/json":{"schema":{"$ref":"#/components/schemas/Payment_Session_Response"}}},"description":"Created payment session"},"403":{"content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error_Response"}}},"description":"Custom wallet not allowed for merchant"},"422":{"content":{"application/json":{"schema":{"$ref":"#/components/schemas/Validation_Error_Response"}}},"description":"Validation error"},"501":{"content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error_Response"}}},"description":"Payment type not available in Phase 1"}},"summary":"Create a payment session","tags":["user"]}}},"components":{"schemas":{"Payment_Session_Request":{"description":"Request to create a payment session (ON_RAMP today; OFF_RAMP returns 501)","properties":{"amount":{"description":"Optional fiat amount.","format":"decimal","type":"string"},"country":{"description":"ISO 3166-1 alpha-2 country code. REQUIRED — no default.","type":"string"},"currency_id":{"description":"Target currency id.","format":"uuid","type":"string"},"custom_wallet_address":{"description":"Self-custody destination. Only honoured when the merchant flag is on.","type":"string"},"metadata":{"description":"Free-form merchant metadata.","type":"object"},"payment_type":{"description":"ON_RAMP routes to MELD. OFF_RAMP is accepted but returns 501 in Phase 1.","enum":["ON_RAMP","OFF_RAMP"],"type":"string"},"redirect_url":{"description":"URL the MELD widget redirects the user to on completion. Required for ON_RAMP; must start with http:// or https://.","type":"string"},"session_reference":{"description":"Merchant's own id for this session; echoed back in webhooks.","type":"string"},"user_reference_id":{"description":"Merchant's stable player id. Required unless custom_wallet_address is supplied.","type":"string"}},"required":["payment_type","country","currency_id"],"title":"Payment_Session_Request","type":"object"},"Payment_Session_Response":{"description":"A created payment session","properties":{"correlation_key":{"description":"Server-generated key, also the provider's externalSessionId.","type":"string"},"expires_at":{"description":"Link expiry. Null until a self-imposed TTL is introduced.","format":"date-time","nullable":true,"type":"string"},"link":{"description":"Provider-hosted URL the user is sent to.","type":"string"}},"required":["link","correlation_key"],"title":"Payment_Session_Response","type":"object"},"Error_Response":{"description":"Error response format","properties":{"error":{"description":"Error flag, always true","type":"boolean"},"message":{"description":"Error message describing what went wrong","type":"string"},"request_id":{"description":"Request correlation ID for tracking and debugging","type":"string"},"status":{"description":"Transaction status when a transaction was created before the error (e.g. `\"failed\"` for a withdrawal that was submitted but failed)","nullable":true,"type":"string"},"transaction_uuid":{"description":"Database transaction UUID (only present when a transaction exists)","format":"uuid","nullable":true,"type":"string"}},"required":["error","message","request_id"],"title":"Error_Response","type":"object"},"Validation_Error_Response":{"description":"Validation error response format","properties":{"error":{"description":"Error message","type":"string"},"errors":{"additionalProperties":{"items":{"type":"string"},"type":"array"},"description":"Field-specific validation errors","type":"object"}},"required":["error","errors"],"title":"Validation_Error_Response","type":"object"}}}}
```


---

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