Google Has Documented Its Replacement for the Custom Search API — and You Can't Have It

Google's developer documentation for the Web Search Service API was updated on 9 September 2026. It describes, in Google's own words, an API that "allows programmatic partners to develop websites and applications that retrieve and display Google Search results."

The operative word is partners. Access requires three things:

1. An active Google Cloud project
2. An API key created in the Google Cloud Console
3. A designated client_id associated with the partner agreement

The first two are self-serve. The third is not. Without an agreement with Google, there is no route in — no billing tier you can upgrade to, no quota you can request.

The timing is the story

This documentation didn't appear in isolation. The Custom Search JSON API — the long-standing, self-serve, publicly available way to get Google results programmatically — carries a deprecation notice with two hard facts:

"Existing Custom Search JSON API customers have until January 1, 2027 to transition to an alternative solution."

"The Custom Search JSON API is closed to new customers."

Already closed. Not closing. If you don't have it today, you cannot get it.

Google's deprecation notice points at two alternatives. Vertex AI Search is recommended as "a favorable alternative for searching up to 50 domains" — which is site search, not web search, and useless for anything resembling rank tracking or SERP analysis. For the other case, Google says:

"if your use case necessitates full web search, contact us to express your interest in and get more information about our full web search solution."

A contact form. That form is the front door to what the Web Search Service API documentation now describes: a GET to websearchservice.googleapis.com/v1:search, requiring clientContext.clientId, userContext.ipAddress and searchQuery.query, returning a SearchResponse in JSON.

So the shape of the transition is now visible. The public door closes on 1 January 2027. The replacement exists, is documented, and is gated.

What this actually means

Programmatic access to Google's index is becoming a commercial relationship rather than a product. A self-serve API with a price list is available to anyone who can pay. A partner agreement is available to whoever Google decides to sign, on terms neither party publishes. Those are different things, and the second gives Google discretion the first never did.

It closes the last officially sanctioned route for small tools. Custom Search JSON was never a great rank-tracking solution — it queried a custom search engine, not raw Google results, and returns diverged from what users saw. But it was permitted, documented and self-serve. After January 2027, an independent developer who wants Google results has no sanctioned option at all. The choice becomes a partner agreement they probably can't get, or scraping.

It lands alongside Google making scraping harder. In late August Google began rolling out goto tracking redirects on result URLs, widely read as targeting tools and scrapers. Squeezing the unsanctioned route while gating the sanctioned one is a coherent position, and the direction of travel is not subtle.

It has implications for AI answer engines specifically. Anything that wants to ground answers in live Google results needs either an agreement or an alternative index. That's a meaningful structural advantage for whoever holds those agreements, and a meaningful cost for everyone else.

What we don't know, and shouldn't guess

The documentation is thin on the things that matter commercially. It states no pricing. It states no rate limits. It sets out no caching, storage or display restrictions on the pages reviewed — which is not the same as there being none, since those terms most likely live in the partner agreement itself rather than in public docs.

Nor does Google define what "full web search" includes, how results relate to what a user sees in a browser, or what the criteria for becoming a partner are. Treat confident claims about any of that as speculation. What's documented is the access model, not the deal.

What to do

If you depend on the Custom Search JSON API, start migrating now. You have until 1 January 2027, and your replacement options are genuinely constrained — this is not a swap-the-endpoint exercise. Audit anything in your stack that calls it, including scripts you inherited and forgot about.

If you were planning to build on it, stop. It's closed to new customers. That plan is already dead.

If your use case is site search across a manageable number of domains, look at Vertex AI Search. Google's own recommendation caps it at 50 domains, and for internal or federated site search it's a reasonable destination.

If you genuinely need full-web results, submit the interest form early. Whatever the criteria are, being in the queue before the shutdown deadline is better than after — and the answer you get tells you whether to plan around having access or not having it.

If you buy SEO tools, ask your vendors where their Google data comes from and what happens in January 2027. Some will have partner agreements. Some will be scraping. Some won't have thought about it. That answer is now a legitimate procurement question, and it bears directly on whether a tool you depend on still works in fifteen months.

Sources

• Google for Developers: Web Search Service API overview
• Google for Developers: Web Search Service API — How to Invoke the API
• Google for Developers: Custom Search JSON API overview and deprecation notice