At its WWDC keynote on June 8, 2026 (US time), Apple revealed a new framework in iOS 27 called Extensions. Until now, the only external AI behind Apple Intelligence was ChatGPT, but Extensions lets users choose outside models such as Claude or Google Gemini and use them as the brain behind Siri and the writing tools. It marks a shift toward an open, competitive Apple Intelligence that is no longer tied to a single provider.
What Extensions Is
Extensions is a framework that opens parts of Apple Intelligence to third-party AI providers. It covers the generative features built into the system, including Siri, the Writing Tools that polish your text, and Image Playground for generating images. These can now hand their processing off to an external model.
Outside AI providers add Extensions support to their existing apps using a dedicated SDK, and the apps are distributed through a dedicated category on the App Store. After installing a supported app, the user picks which AI to use from the Apple Intelligence and Siri section of Settings. Conceptually, it extends the idea behind third-party keyboards and share-sheet extensions into the realm of generative AI.
Swapping Out the AI Behind Siri
The biggest change is that users can choose the system's default AI. The model selected in Settings applies across the whole device, so requests to Siri, edits in the Writing Tools, and image generation in Image Playground are all routed to the chosen AI.
The names floated as options include OpenAI's ChatGPT, Anthropic's Claude, Google Gemini, and xAI's Grok. There are also indications that, in the future, users may be able to assign different models to different tasks. For example, Gemini for research, Claude for coding help, and ChatGPT for writing, switching between them based on each model's strengths. This breaks the previous ChatGPT-exclusive arrangement and turns Apple Intelligence into a level playing field where several AIs compete side by side.
This Extensions system is separate from the separately announced effort to rebuild the foundation of Siri itself on a custom Google Gemini model. The model that underpins Siri and the model that users layer on top and swap out are treated as two different things.
What It Means for the Major AI Companies
Extensions matters not just for Apple but for the AI companies as well. Apple devices are used at a scale of more than 1 billion units worldwide, so winning the default-AI slot would instantly give each company an enormous point of contact. For Anthropic, OpenAI, and Google, their own apps become an on-ramp into the whole of Apple Intelligence.
Apple is reported to be testing Claude and Gemini as its initial partners, alongside the existing ChatGPT integration. Going forward, it appears to envision an open arrangement in which any AI provider that meets the SDK requirements can take part. Moving from one-off deals with a single company to a platform anyone qualified can join, Apple's position looks to be shifting from an AI provider to the operator of a marketplace where users choose.
Supported Devices and Timing
The new Apple Intelligence features, including Extensions, are expected to work on iPhone 15 Pro and iPhone 16 or later. The features entered developer testing right after WWDC, and they are scheduled to reach general users this fall when the final version of iOS 27 arrives. Exactly how far each AI can integrate will become clearer through the fall release, together with the arrival of supported apps.
Summary
iOS 27's Extensions is a major change of direction that lets users themselves choose the AI behind Apple Intelligence. Moving from a ChatGPT-only state to a lineup that includes Claude and Gemini side by side, users can set the AI best suited to their needs as their device's brain. For the AI companies, it sets the stage for a new fight over an enormous customer base, and attention now turns to what kind of Extensions each company will bring for this fall's official release.
