> ## Documentation Index > Fetch the complete documentation index at: https://docs.topsort.com/llms.txt > Use this file to discover all available pages before exploring further. # Get Campaign Billing Contact > Get the billing contact assigned to a campaign. Call this on demand, when a shopper clicks to see an ad's details (for example an "About this ad" link). Auction winners include a `campaignId`, and the returned contact gives you the advertiser and payer details to display, as the Digital Services Act (DSA) requires. You don't need it to render the ad itself. Call it from your backend, never from a browser or app. You can cache the result per campaign for a few minutes. Returns `404` if the campaign has no billing contact or isn't in your marketplace. See the [DSA setup guide](https://docs.topsort.com/en/ad-server/additional-apis/digital-services-act). ## OpenAPI ````yaml /openapi.json get /public/v1/billing-service/campaign-billing-contact openapi: 3.1.0 info: title: Topsort Endpoints v2 API Reference description: > In order for a storefront to be able to run auctions in Topsort and report auction-related events back to Topsort, both the `/v2/auctions` and `/v2/events` endpoints must be integrated. Below are the endpoint and model definitions for each. contact: email: wicha@topsort.com license: name: Apache 2.0 url: http://www.apache.org/licenses/LICENSE-2.0.html x-logo: url: https://assets.topsort.com/Topsort_logo_icon_dark.svg backgroundColor: '#fff' altText: Topsort version: 2.0.0 servers: - url: https://api.topsort.com description: Base API URL security: [] tags: - name: Auctions description: >- An auction determines which products should be promoted based on the vendors' bids. - name: Events description: >- Events are sent to Topsort as part of the attribution and reporting journey. - name: Toptimize description: > An out-of-the-box solution for prediction, ranking, retrieval, and other elements of ad selection. - name: Toppie API description: Toppie management API. - name: Campaign API description: Full-featured campaign management API for banners and sponsored listings. - name: Catalog API description: Products catalog management API. - name: Billing API description: Marketplace and Vendor Billing management API. - name: Reporting API description: Marketplace, Vendor, Campaign, and product reporting API. - name: Invitation API description: Vendor invitations management API. - name: User API description: User management API. - name: Webhooks API description: Webhooks API that allows event-driven automation. - name: Assets API description: Assets management API. - name: Segments Service description: Segments Service. - name: Forecasting Service description: Toptimize Forecasting Service. - name: Offsite Ads API description: Offsite Ads API that allows to manage offsite ads campaigns. - name: Media API description: Ad configuration API. - name: Placement API description: Placement management API for sponsored brand slots. - name: Export API description: Request an asynchronous Parquet export of your performance data. paths: /public/v1/billing-service/campaign-billing-contact: get: tags: - Billing API summary: Get Campaign Billing Contact description: >- Get the billing contact assigned to a campaign. Call this on demand, when a shopper clicks to see an ad's details (for example an "About this ad" link). Auction winners include a `campaignId`, and the returned contact gives you the advertiser and payer details to display, as the Digital Services Act (DSA) requires. You don't need it to render the ad itself. Call it from your backend, never from a browser or app. You can cache the result per campaign for a few minutes. Returns `404` if the campaign has no billing contact or isn't in your marketplace. See the [DSA setup guide](https://docs.topsort.com/en/ad-server/additional-apis/digital-services-act). operationId: get_campaign_billing_contact parameters: - name: campaign_id in: query required: true schema: type: string format: uuid description: The ID of the campaign to get the billing contact for. title: Campaign Id description: The ID of the campaign to get the billing contact for. responses: '200': description: Successful Response content: application/json: schema: $ref: '#/components/schemas/Advanced_APIs_PublicBillingContact' '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/Advanced_APIs_HTTPValidationError' security: - Advanced_APIs_HTTPBearer: [] components: schemas: Advanced_APIs_PublicBillingContact: properties: id: type: string title: Id description: The ID of the billing contact. brandName: type: string title: Brandname description: The name of the brand this agency is advertising for. invoiceTo: type: string title: Invoiceto description: The name of the company that is responsible for the invoice. advertiserName: type: string title: Advertisername description: The name of the agency/advertiser. type: object required: - id - brandName - invoiceTo - advertiserName title: PublicBillingContact Advanced_APIs_HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/Advanced_APIs_ValidationError' type: array title: Detail type: object title: HTTPValidationError Advanced_APIs_ValidationError: properties: loc: items: oneOf: - type: string - type: integer type: array title: Location msg: type: string title: Message type: type: string title: Error Type type: object required: - loc - msg - type title: ValidationError securitySchemes: Advanced_APIs_HTTPBearer: type: http description: >- A valid API key generated in Topsort's UI. Use the TSE API key if calling auctions or events API, otherwise use the TSC API key. scheme: bearer ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.