Opera on 27 October 2026 released a test version of WebAI, a proposed standard that lets websites and browser extensions use an AI model running on the user's own computer instead of in the cloud. Processing stays on the device. Opera's post does not say what the web page does with the answer it gets back.
Opera One is the company's first browser with built-in access to local models. Opera GX and Opera Neon will get it later. Opera says companies such as Google and Microsoft back the proposal. Krystian Kolondra, Opera's vice president for browsers and AI, says: "A lot of what people want from AI doesn't need a data center."
Three interfaces and a choice of models
A local model is a language model that is downloaded to the device and runs there. The text you give it does not travel to another company's server. Developers do not need their own infrastructure, an access key or a payment for each request.
Opera is introducing three programming interfaces. Prompt generates text, Decision sorts content into categories, and Semantic Embeddings finds links between texts, for example which paragraphs are close in meaning. Opera's developer page also lists Summarizer, Writer, Rewriter, Translator and Proofreader.
The browser has no ready-made button for summarising, translating or searching. The test extensions are experimental and are not Opera features. One shades an article by how closely each paragraph relates to the reader's work. Another quizzes the reader on what they have read. Other examples include sorting tabs, spotting clickbait and finding suitable job ads.
Users can choose the model. Opera offers open models through its own engine and can also use compatible models already on the device. At launch, Google's Gemma is available, and on Mac so is Apple's built-in model.
WebAI runs on 64-bit Windows with an Intel or AMD processor, and on Macs with an Apple chip. Intel Macs, Linux and Windows on Arm are not supported. Speed depends on the machine. In Opera's earlier tests with local models, each one usually took up 2 to 10 GB.
WebAI is off by default
To turn it on, go to Settings, then Opera AI (or opera://settings/ai) and use the Web AI API switch. The browser then downloads a model, which can take a few minutes. It can be turned off in the same place.
Opera says users decide which sites can use the local AI. Another outlet reports that sites and extensions must get explicit approval before they use the graphics card and memory. A third outlet found no description of prompts for individual sites or extensions. Opera's blog does not mention per-site permissions.
Opera says data handled by the local AI does not have to go to a cloud provider. Another review says the processing sends no traffic to Opera's servers. The same review notes that the browser itself still sees history, bookmarks and traffic through the built-in VPN.
Opera does not say whether a site can pass the model's answer on to its own server. Documentation for the similar Prompt API in Chrome describes access through JavaScript, where the page can fall back to a cloud service.
Chrome's Prompt API and the objections to it
Google released the Prompt API in Chrome 148 on 5 May 2026. It uses the Gemini Nano model, which Chrome downloaded without asking, about 4.27 GB, and downloads again if the user deletes it. Developers must accept Google's policy on prohibited uses of generative AI. One review says Opera is working to the same specification, but with open models and without such an agreement.
Mozilla and Apple formally oppose the Prompt API. Jake Archibald of Mozilla writes that the API has "severe negative consequences to the interoperability, updatability, and neutrality of the web platform". His main argument is that developers will tune their prompts to one model, and the prompts may not work in another browser.
Maciej Stachowiak of WebKit warned that sites will become tied to the quirks of one model. The W3C's Technical Architecture Group also filed formal objections. Microsoft voiced concerns and switched the feature off in Edge until 5 May.
Opera has given no release date beyond the preview, which is for now only in Opera One.