# Alto (Vebra / Zoopla) — API surface > Alto, formerly Vebra Alto, is the United Kingdom's most widely deployed estate agency CRM, used by > more than 6,000 sales and lettings agencies and owned by Houseful, the parent of the Zoopla portal. > The UK has no MLS, so listings reach Rightmove and Zoopla through agency CRM software rather than a > shared cooperative database, and Alto is the largest of those pipes. The contract is open and the > access is closed: a complete OpenAPI 3.0.4 document (112 operations across 27 resource families) and > a 26-event CloudEvents 1.0 webhook catalogue are published anonymously, while credentials require an > existing contract with Vebra Solutions, an integration registered in Alto Connect, and per-agency > activation. Three sibling Zoopla portal product APIs are documented on the same terms. This file is generated by API Evangelist from the provider's published artifacts. Alto's own llms.txt (`alto-vebra-llms.txt` in this directory, fetched from https://www.altosoftware.co.uk/llms.txt) is a product/marketing document that does not mention the API at all. ## APIs - [Alto API](https://developers.vebraalto.com/api): 112 operations over contacts and applicants, property inventory, listings and media, appraisals, appointments, leads, offers, sales and lettings progression, tenancies, landlords, work orders, suppliers, documents, file notes, branches, negotiators and partner integration status. Base URL https://api.alto.zoopla.co.uk (production), https://api.alto.zoopladev.co.uk (sandbox). - [Zoopla Leads API](https://developers.zoopla.co.uk/leads/reference/api): poll applicant and appraisal leads generated on the Zoopla portal. Base URL https://services.zoopla.co.uk. - [Zoopla Premium Listing Activations API](https://developers.zoopla.co.uk/premium-listings/reference/api): activate and inspect the Premium Listing product against a listing. Billable. - [Zoopla Weekly Featured Property (WFP) Activations API](https://developers.zoopla.co.uk/wfp/reference/api): activate a Weekly Featured Property placement. Billable. ## Specs - [Alto API OpenAPI 3.0.4](https://api-docs.vebraalto.com/merged.json): served anonymously, no key, no login - [Zoopla Leads Swagger 2.0](https://developers.zoopla.co.uk/leads/reference/leads-poll.json) - [Zoopla Premium Listings OpenAPI 3.0.0](https://developers.zoopla.co.uk/premium-listings/reference/pl-spec.json) - [Zoopla WFP OpenAPI 3.0.0](https://developers.zoopla.co.uk/wfp/reference/wfp-spec.json) ## Events - [Alto webhooks](https://developers.vebraalto.com/guides/webhooks/): 26 CloudEvents 1.0 event types across contacts, properties, branches, appointments, tenancies, offers, sales progression, leads and integration state. Notifications carry ids only — re-fetch the resource. Retried up to 10 times over 6 hours; delivery order is not guaranteed; de-duplicate on the `id` field. Subscriptions are configured manually by Alto on email request. - [Zoopla lead push service](https://developers.zoopla.co.uk/leads/docs/push-service): real-time delivery of the same payload the polled Leads API returns. Retried for 24 hours; leads retained 30 days; no automatic replay. ## Authentication - [Authenticating your requests (Alto)](https://developers.vebraalto.com/guides/authenticating-your-requests/): OAuth 2.0 client credentials against https://api.alto.zoopladev.co.uk/token producing a Bearer JWT, plus a per-agency `AgencyRef` header on every call. 401 means the token is wrong; 403 means the AgencyRef or scope is wrong. - [Authentication (Zoopla)](https://developers.zoopla.co.uk/docs/authentication): OAuth 2.0 client credentials against https://services-auth.services.zoopla.co.uk/oauth2/token. The client_secret is delivered PGP-encrypted to a public key the partner supplies. - 101 Alto scope strings are published in operation description prose rather than in the securitySchemes object; the Zoopla product APIs use a single coarse `api/api_access` scope. ## Docs - [Alto developer documentation](https://developers.vebraalto.com/) - [Alto API reference](https://developers.vebraalto.com/api) - [Help with error response codes](https://developers.vebraalto.com/guides/error-codes/) - [Glossary](https://developers.vebraalto.com/guides/glossary/) - [Access to sandbox Alto UI](https://developers.vebraalto.com/guides/access-to-sandbox-alto-ui/) - [Activation request emails](https://developers.vebraalto.com/guides/activation-request-emails/) - [Guide for referencing partners](https://developers.vebraalto.com/guides/guide-for-referencing-partners/) - [Guide for storing email conversations in file notes](https://developers.vebraalto.com/guides/guide-for-storing-email-conversations-in-filenotes/) - [API terms of use](https://developers.vebraalto.com/api-terms-of-use) - [Zoopla docs](https://developers.zoopla.co.uk/) - [Premium Listings error code register](https://developers.zoopla.co.uk/docs/premium-listings-error-codes-register) - [Weekly Featured Properties error code register](https://developers.zoopla.co.uk/docs/weekly-featured-properties-error-code-register) ## Reference data - [Appraisal types](https://developers.vebraalto.com/alto-data/appraisal-types/) - [Phone number types](https://developers.vebraalto.com/alto-data/phone-number-types/) - [Property statuses](https://developers.vebraalto.com/alto-data/property-statuses/) - [Property types](https://developers.vebraalto.com/alto-data/property-types/) - [Rental frequencies](https://developers.vebraalto.com/alto-data/rental-frequencies/) - [Rental price qualifiers](https://developers.vebraalto.com/alto-data/rental-price-qualifiers/) - [Returning tenancies and tenants](https://developers.vebraalto.com/alto-data/returning-tenancies-and-tenants/) - [Sequencing order](https://developers.vebraalto.com/alto-data/sequencing-order/) - [Tenancy duration](https://developers.vebraalto.com/alto-data/tenancy-duration/) - [Tenancy statuses](https://developers.vebraalto.com/alto-data/tenancy-statuses/) ## Access - [Alto Connect](https://connect.vebraalto.com/connect): register an integration. Partner login, not a public developer signup. - [Become a partner](https://www.altosoftware.co.uk/become-a-partner/) - [Partner feedback / issue submission](https://partnerfeedback.vebraalto.com/) - Webhook subscriptions and sandbox passwords: connectsupport@altosoftwaregroup.co.uk - Zoopla API onboarding: members@zoopla.co.uk ## Optional - [Alto integrations directory](https://www.altosoftware.co.uk/integrations/): 39 published partner integrations - [Alto product release notes](https://files.vebraalto.com/alto/downloads/): unindexed PDFs; there is no API changelog - No SDK, no CLI, no Postman collection and no MCP server is published in any language. - No status page exists on any host in this estate. - No RESO Web API or Data Dictionary certification exists; RESO is a North American standard with no UK counterpart.