Google makes its Web Search Service API partner-only as Custom Search closes

Google updated the developer documentation for the Web Search Service API on 9 September 2026, and the pages now describe it as the successor to the Custom Search JSON API for teams that need full-web results. Search Engine Journal's Matt G. Southern documented the change on 11 September. Google's own overview page states that the API "allows programmatic partners to develop websites and applications that retrieve and display Google Search results" and that every request must carry a client ID tied to a partner agreement, on top of a Google Cloud project and API key.

The other part of the story is the deadline. The Custom Search JSON API overview page now reads: "existing Custom Search JSON API customers have until January 1, 2027 to transition to an alternative solution", and the API is closed to new customers. Google had already told teams needing full-web results back in January to get in touch about a separate solution; the September pages are the first time that solution has a documented API surface.

What the Web Search Service API actually offers

Google documents a single primary method, Search, which performs a full web search and returns JSON over REST or gRPC. Search Engine Journal reports that each request must carry a partner client ID, the user's IP address, and the query string, and that Google's guide says the IP address supports regional routing and helps prevent misuse. Response payloads include title, URL, snippet, MIME type, file format, an estimated total result count, and a corrected query when Google recommends one. A request returns up to 20 results, ten by default, with paging tokens for more. Filters cover language, country, date range, SafeSearch and date sorting.

The partner gate is the point. Search Engine Journal notes that the docs describe users as "programmatic partners", and that the client ID format includes partner, product and feature-set fields. Google's pages do not publish pricing, quota limits, or the criteria for becoming a partner; interested teams are asked to fill in a form.

Who this affects

Two paths converge on this API. Anyone who has been calling the Custom Search JSON API across the whole web, rather than a set of fewer than 50 configured sites, has to switch by 1 January 2027 or lose the results. And anyone who was using the Programmable Search Element as a widget on more than 50 domains has the same deadline: Google refocused that widget on small-site search back in January and directed enterprise use to Vertex AI Search or the full-web API.

That covers a longer list of tools than it first appears. Internal search dashboards, SEO tools that check how a query looks in Google today, AI grounding steps that fetch live citations for an answer, competitive-monitoring pipelines, and rank trackers all rely on either the JSON API or a scraper that Google would rather they replace. For teams building agents that ground on live web results, this is the officially documented Google path, but it now requires a partner relationship rather than a self-serve API key.

The site-restricted alternative is still self-serve: the Programmable Search Engine and its embed continue to work within a small set of domains. Vertex AI Search is Google's enterprise search product on Google Cloud and is the option Google directs grounding and conversational use to.

Search Engine Journal notes that as of 11 September, neither Google's January announcement nor the refreshed Web Search Service pages mention each other, so a team reading only one will miss how the change fits together.

Source

Search Engine Journal, Google Documents Partner-Only API For Full-Web Search Results. Google's own pages, Web Search Service API overview and Custom Search JSON API overview.