--- title: Client Registration API description: "Use the Client Registration API to register a new regulated third-party financial application with eBay. This API is intended for regulated Third Party Providers (TPPs) who are, or will be, engaged in financial transactions on behalf of individuals domiciled in the EU or UK. The Client Registration API supports Dynamic Client Registration for payment-services workflows that are subject to EU and UK payment-services regulations. A successful registration returns HTTP status code 201 Created and client registration information." api_version: 1.0 api_name: client_registration_api api_type: REST api_group: sell/client_registration_api source_url: html: https://developer.ebay.com/develop/api/sell/client_registration_api md: https://developer.ebay.com/develop/api/sell/client_registration_api.md --- # Client Registration API API Use the Client Registration API to register a new regulated third-party financial application with eBay. This API is intended for regulated Third Party Providers (TPPs) who are, or will be, engaged in financial transactions on behalf of individuals domiciled in the EU or UK. The Client Registration API supports Dynamic Client Registration for payment-services workflows that are subject to EU and UK payment-services regulations. A successful registration returns HTTP status code 201 Created and client registration information. ## API Methods The following API methods are available: ### registerClient #### POST /client/register **Description:** **Note:** The Client Registration API is not intended for use by developers who have previously registered for a Developer Account on the eBay platform. This call registers a new third party financial application with eBay. **Important!** When calling the **registerClient** method, Third Party Providers (TPPs) are required to pass their valid eIDAS certificate to eBay via Mutual Transport Layer Security (MTLS) handshake _Certificate Request_ messages. A successful call returns an HTTP status code of **201 Created** and the response payload. #### Registering multiple applications A regulated third party provider (identified by a unique _organizationIdentifier_) may register up to 15 different applications with eBay provided the unique [software\_id](#request.software_id) for each application is passed in at the time of registration. Each **registerClient** call that passes in a unique [software\_id](#request.software_id) will generate new [client\_id](#response.client_id) and [client\_secret](#response.client_secret) keypairs. If a third party provider calls **registerClient** using a previously registered [software\_id](#request.software_id), the existing [client\_id](#response.client_id) and [client\_secret](#response.client_secret) keypairs are returned. **Note:** For additional information about using an _organizationIdentifier_, refer to the following sections of [ETSI Technical Specification 119 495](https://www.etsi.org/deliver/etsi_ts/119400_119499/119495/01.05.01_60/ts_119495v010501p.pdf): * Section 5.2.1: Authorization Number or other recognized identifier for Open Banking; * Section 5.4: Profile Requirements for Digital Signatures. **Parameters:** - **Content-Type** (string) *required* - This header indicates the format of the request body provided by the client. Its value should be set to **application/json**. For more information, refer to [HTTP request headers](/develop/guides-v2/using-ebay-restful-apis#request-components). ## Error Codes The following error codes may be returned by this API: ### REQUEST Errors #### invalid_policy_uri - CLIENT_REGISTRATION **Description:** The policy\_uri presented is invalid. #### invalid_contact_email - CLIENT_REGISTRATION **Description:** The value of one or more of the contact email addresses is invalid. #### invalid_software_statement - CLIENT_REGISTRATION **Description:** The software statement presented is invalid. #### invalid redirect_uri - CLIENT_REGISTRATION **Description:** The value of one or more redirection URIs is invalid or missing. #### invalid_request - CLIENT_REGISTRATION **Description:** Empty request or some field has error. #### maximum_limit_keysets_reached - CLIENT_REGISTRATION **Description:** You have exceeded the maximum number of API keysets. For more information, see the API call reference documentation. #### caller_not_registered - CLIENT_REGISTRATION **Description:** Caller is not registered #### invalid_license - CLIENT_REGISTRATION **Description:** Invalid license #### invalid_qtsp - CLIENT_REGISTRATION **Description:** Certificate not issued by a valid Qtsp #### certificate_expired - CLIENT_REGISTRATION **Description:** Certificate expired #### certificate_revoked - CLIENT_REGISTRATION **Description:** Certificate revoked #### invalid_signature - CLIENT_REGISTRATION **Description:** Not a valid signature #### role_mismatch - CLIENT_REGISTRATION **Description:** Role not matching #### invalid_certificate - CLIENT_REGISTRATION **Description:** Invalid certificate #### missing_certificate - CLIENT_REGISTRATION **Description:** Missing certificate #### certificate_validation_error - CLIENT_REGISTRATION **Description:** Internal errors as validating client certificate ### APPLICATION Errors #### internal_server_error - CLIENT_REGISTRATION **Description:** There was a problem with an eBay internal system or process. Please retry. #### internal_service_error - CLIENT_REGISTRATION **Description:** Internal errors as calling another service ## Rate Limits See [API Call Limits](https://developer.ebay.com/develop/get-started/api-call-limits) on the eBay Developer Program. ## Resources ### Documentation - [eBay Developer Program](https://developer.ebay.com/) - [API Documentation](https://developer.ebay.com/develop/api/) - [SDKs and Widgets](https://developer.ebay.com/develop/sdks-and-widgets) - [Developer Community Forum](https://community.ebay.com/t5/Developer-Groups/ct-p/developergroup) ### Tools - [API Explorer](https://developer.ebay.com/my/api_test_tool) - [GraphQL Explorer](https://developer.ebay.com/my/graphql_explorer) ### Support - [Developer Support](https://developer.ebay.com/support/) - [API Status](https://developer.ebay.com/support/api-status) - [Release Notes](https://developer.ebay.com/develop/api/release_notes/) --- *Generated on 2026-07-08T04:36:59.789Z*