Thomas Steiner
Published: May 14, 2026
With the Prompt API in Chrome, you can interact with an LLM using a high-level browser API on window.LanguageModel. However there is still limited support for this and implementation is a complex process.
| Browser | Supported OS | Unsupported OS | Position |
|---|---|---|---|
| Chrome | Windows, macOS, Linux, ChromeOS (Chromebook Plus) | Android, iOS | ✅ Supported |
| Edge | Windows, macOS | Android, iOS | ✅ Supported |
| Safari | — | — | 📋 Position decided |
| Firefox | — | — | 📋 Position decided |
At the same time, developers in the early preview program have shared their enthusiasm for the Prompt API. The availability of the API poses a compatibility challenge for the foreseeable future.
Solution
This is why we are releasing an experimental spec-compliant Prompt API polyfill (see the source code on GitHub) that accurately implements the Prompt API on top of configurable cloud backend providers and also on top of a local backend provider in the form of Transformers.js.