> ## Documentation Index > Fetch the complete documentation index at: https://docs.mnai.com/llms.txt > Use this file to discover all available pages before exploring further. # Create a Session > Create a Realtime Collections session to obtain the session key required to create payment links. ## OpenAPI ````yaml products/realtime-collections/api-reference/payment-links.json POST /v1/payment-links/sessions openapi: 3.1.0 info: title: Realtime Collections API description: >- Partner API for Meridian Realtime Collections: operator sessions, and creating, updating, and retrieving payment links used to collect funds from customers. version: 1.0.0 servers: - url: https://us-merchant.sandbox.api-us.meridianapps.dev description: Sandbox - url: https://us-merchant.api-us.payments.meridianpay.com description: Production security: [] tags: [] externalDocs: url: / paths: /v1/payment-links/sessions: post: tags: - Sessions summary: Create a Realtime Collections Session description: >- Validates the supplied credentials and returns a session key used to create payment links. Session keys expire after 15 minutes. The session key is tied to the operator data supplied here, so if anything about the operator changes you must obtain a new key. This endpoint does not perform duplicate-payload checks: a new session key is generated on every call. operationId: createPaymentLinksSessions parameters: - $ref: '#/components/parameters/MeridianApiKeyHeader' - $ref: '#/components/parameters/MeridianTimestampHeader' requestBody: description: >- Operator context used for auditing when creating a Realtime Collections API session. content: application/json: schema: $ref: '#/components/schemas/CreatePaymentLinkSessionRequest' examples: PaymentLinkSessionRequest: $ref: '#/components/examples/PaymentLinkSessionRequest' required: true responses: '201': description: Created the session and stored the contents for later use headers: {} content: application/json: schema: $ref: '#/components/schemas/CreatePaymentLinkSessionResponse' examples: PaymentLinkSessionCreated: $ref: '#/components/examples/PaymentLinkSessionCreated' '400': description: >- Malformed or invalid submission. Also returned when the API key is valid but does not belong to a merchant. headers: {} content: application/json: schema: $ref: '#/components/schemas/MeridianError' '401': description: >- Missing, unknown, or incorrectly signed API key. The response body is empty. headers: {} '500': description: Internal Server Error headers: {} content: application/json: schema: $ref: '#/components/schemas/MeridianError' deprecated: false security: - MeridianHmacAuth: [] components: parameters: MeridianApiKeyHeader: name: X-Meridian-Api-Key in: header required: true description: API key issued by Meridian during provisioning. schema: type: string example: your-api-key MeridianTimestampHeader: name: X-Meridian-Timestamp in: header required: true description: >- Current time in milliseconds since the Unix epoch. Must be within 10 seconds of the request. schema: type: string example: '1749566400000' schemas: CreatePaymentLinkSessionRequest: type: object description: >- Operator context used for auditing when creating a Realtime Collections API session. properties: operatorId: type: string description: >- Unique identifier of the operator (user) initiating the session in the merchant system. Used for audit and traceability; must be present and non-blank but is not otherwise validated. title: String operatorName: type: string description: >- Human-readable name of the operator (user) initiating the session, stored for audit logs so actions can be attributed to a specific person. title: String required: - operatorId - operatorName title: CreatePaymentLinkSessionRequest CreatePaymentLinkSessionResponse: type: object description: >- Session key issued for the Realtime Collections API, valid for 15 minutes. properties: sessionKey: type: string description: >- Unique session key to pass in the body of the create-payment-link request. title: String expiresAt: type: string format: date-time description: >- ISO-8601 datetime (UTC) at which the session key expires, 15 minutes after it was issued. title: String required: - sessionKey - expiresAt title: CreatePaymentLinkSessionResponse MeridianError: type: object description: >- Standard error response returned when a request cannot be completed. Includes a human-readable message and, for validation failures, a list of field-level errors. properties: validationErrors: type: array description: >- List of field-level validation errors, empty when the failure is not validation-related. items: $ref: '#/components/schemas/ValidationError' title: Array_ValidationError message: type: string description: Human-readable description of the error. title: String errorCode: type: string description: >- Machine-readable error code identifying the failure. Omitted when no specific code applies. title: String required: - validationErrors - message title: MeridianError ValidationError: description: >- A single validation error describing why a specific field or parameter was rejected. The `type` property identifies which variant it is. oneOf: - $ref: '#/components/schemas/InvalidFormat' - $ref: '#/components/schemas/InvalidValue' - $ref: '#/components/schemas/MissingPathParameter' - $ref: '#/components/schemas/MissingQueryParameter' - $ref: '#/components/schemas/MissingRequestBody' - $ref: '#/components/schemas/MissingValue' - $ref: '#/components/schemas/NotFound' - $ref: '#/components/schemas/UnexpectedVerificationError' - $ref: '#/components/schemas/UnprocessableValue' - $ref: '#/components/schemas/Unknown' discriminator: propertyName: type mapping: InvalidFormat: $ref: '#/components/schemas/InvalidFormat' InvalidValue: $ref: '#/components/schemas/InvalidValue' MissingPathParameter: $ref: '#/components/schemas/MissingPathParameter' MissingQueryParameter: $ref: '#/components/schemas/MissingQueryParameter' MissingRequestBody: $ref: '#/components/schemas/MissingRequestBody' MissingValue: $ref: '#/components/schemas/MissingValue' NotFound: $ref: '#/components/schemas/NotFound' UnexpectedVerificationError: $ref: '#/components/schemas/UnexpectedVerificationError' UnprocessableValue: $ref: '#/components/schemas/UnprocessableValue' Unknown: $ref: '#/components/schemas/Unknown' title: ValidationError InvalidFormat: type: object description: A field was supplied in a format the API could not interpret. properties: type: type: string enum: - InvalidFormat description: Validation error type discriminator. fieldRef: type: string description: Reference to the request field that caused the validation error. title: String message: type: string description: Human-readable explanation of why the field failed validation. title: String required: - type - fieldRef - message title: InvalidFormat InvalidValue: type: object description: A field was well-formed but its value is not allowed. properties: type: type: string enum: - InvalidValue description: Validation error type discriminator. fieldRef: type: string description: Reference to the request field that caused the validation error. title: String message: type: string description: Human-readable explanation of why the field failed validation. title: String required: - type - fieldRef - message title: InvalidValue MissingPathParameter: type: object description: A required path parameter was missing from the request URL. properties: type: type: string enum: - MissingPathParameter description: Validation error type discriminator. fieldRef: type: string description: Name of the path parameter that was missing. title: String message: type: string description: Human-readable explanation of why the parameter failed validation. title: String required: - type - fieldRef - message title: MissingPathParameter MissingQueryParameter: type: object description: A required query parameter was missing from the request URL. properties: type: type: string enum: - MissingQueryParameter description: Validation error type discriminator. fieldRef: type: string description: Name of the query parameter that was missing. title: String message: type: string description: Human-readable explanation of why the parameter failed validation. title: String required: - type - fieldRef - message title: MissingQueryParameter MissingRequestBody: type: object description: The request body was absent, or was missing fields that may not be null. properties: type: type: string enum: - MissingRequestBody description: Validation error type discriminator. fieldRef: type: string description: Always `requestBody` for this error type. title: String message: type: string description: >- Human-readable explanation of why the request body failed validation. title: String required: - type - fieldRef - message title: MissingRequestBody MissingValue: type: object description: A required field was missing from the request body. properties: type: type: string enum: - MissingValue description: Validation error type discriminator. fieldRef: type: string description: Reference to the request field that was missing. title: String message: type: string description: Human-readable explanation of why the field failed validation. title: String required: - type - fieldRef - message title: MissingValue NotFound: type: object description: A referenced resource could not be found. properties: type: type: string enum: - NotFound description: Validation error type discriminator. fieldRef: type: string description: >- Reference to the request field naming the resource that was not found. title: String message: type: string description: Human-readable explanation of what could not be found. title: String required: - type - fieldRef - message title: NotFound UnexpectedVerificationError: type: object description: An unexpected error occurred while verifying the value of a field. properties: type: type: string enum: - UnexpectedVerificationError description: Validation error type discriminator. fieldRef: type: string description: Reference to the request field that could not be verified. title: String message: type: string description: Human-readable explanation of the verification failure. title: String required: - type - fieldRef - message title: UnexpectedVerificationError UnprocessableValue: type: object description: >- A field was valid in isolation but cannot be processed in the context of this request. properties: type: type: string enum: - UnprocessableValue description: Validation error type discriminator. fieldRef: type: string description: Reference to the request field that could not be processed. title: String message: type: string description: Human-readable explanation of why the field could not be processed. title: String required: - type - fieldRef - message title: UnprocessableValue Unknown: type: object description: >- The request was rejected but the specific field at fault could not be determined. properties: type: type: string enum: - Unknown description: Validation error type discriminator. fieldRef: type: string description: Always `unknown` for this error type. title: String message: type: string description: Human-readable explanation of the failure. title: String required: - type - fieldRef - message title: Unknown examples: PaymentLinkSessionRequest: summary: Operator initiating a session value: operatorId: op-123 operatorName: Carlos Tester PaymentLinkSessionCreated: summary: Session key issued value: sessionKey: uslocal-b1x2k0dzsbpc4cz8c8xrvfel expiresAt: '2026-07-02T20:45:50Z' securitySchemes: MeridianHmacAuth: type: apiKey in: header name: X-Meridian-Signature description: >- Meridian HMAC header authentication. Required headers: - X-Meridian-Api-Key - X-Meridian-Timestamp - X-Meridian-Signature X-Meridian-Signature is the HMAC SHA-256 signature of the canonical request string, computed per request as HMAC-SHA256(apiKey + timestamp + method + request URI including any query string + body). See [Authentication](/products/realtime-collections/authentication) for how to construct it. ````