LanguageModelLimited availability

The LanguageModel API prompts an on-device language model. Also known as the Prompt API.

Not yet supported in all major browsers — check the table and provide a fallback.

How to use ↓Compare browsers

Browser support

DesktopChrome

1–147Not supported

148+Supportedsince May 5, 2026

Current: 155

Edge

✕Not supportedup to 154

Current: 154

Firefox

✕Not supportedup to 157

Current: 157

Safari

✕Not supportedup to 27

Current: 27

MobileChrome Android

✕Not supportedup to 155

Current: 155

Firefox Android

✕Not supportedup to 157

Current: 157

Safari iOS

✕Not supportedup to 27

Current: 27

How to use

Not supported in Edge, Firefox, Safari, Chrome Android, Firefox Android, Safari iOS. Use feature detection below and provide a fallback (or a polyfill) for those browsers.

Example

Full syntax and examples are on MDN: LanguageModel.

Feature detection

JS · check before using

if ("LanguageModel" in globalThis) {
  // LanguageModel is available
} else {
  // load a polyfill or use a fallback
}

Documentation (MDN)

Specification

webmachinelearning.github.io/prompt-api ↗

Sub-features

Support for each part of the feature (12). The overall table above shows when the whole feature works.

Sub-feature	Chrome	Edge	Firefox	Safari	Chrome Android	Firefox Android	Safari iOS
LanguageModel	148	✕	✕	✕	✕	✕	✕
LanguageModel.append	148	✕	✕	✕	✕	✕	✕
LanguageModel.availability_static	148	✕	✕	✕	✕	✕	✕
LanguageModel.clone	148	✕	✕	✕	✕	✕	✕
LanguageModel.contextUsage	148	✕	✕	✕	✕	✕	✕
LanguageModel.contextWindow	148	✕	✕	✕	✕	✕	✕
LanguageModel.contextoverflow_event	148	✕	✕	✕	✕	✕	✕
LanguageModel.create_static	148	✕	✕	✕	✕	✕	✕
LanguageModel.destroy	148	✕	✕	✕	✕	✕	✕
LanguageModel.measureContextUsage	148	✕	✕	✕	✕	✕	✕
LanguageModel.prompt	148	✕	✕	✕	✕	✕	✕
LanguageModel.promptStreaming	148	✕	✕	✕	✕	✕	✕