Skip to main content

Which Browsers Support WebMCP Today

Short answer

As of October 20, 2026, no browser ships WebMCP to all users. Chrome lets a site opt in through an origin trial, starting with Chrome 149, and offers a flag for local testing. Edge runs its own origin trial from Edge 150. Firefox has a neutral position on WebMCP and Safari's engine, WebKit, has an opposing one, so neither has an implementation. Check the table below before you build anything that depends on it.

Tested withChrome 149 (stable June 2, 2026)Chrome 150 release notesMicrosoft Edge 150 (July 2, 2026)Checked 20 Oct 2026

By Tony LewisHow we test these guides

Status by browser​

BrowserStatus todayVersion and dateSource
Chrome (desktop, Android, WebView)Origin trial, plus a flag for local testingTrial open from Chrome 149, which reached stable on June 2, 2026Chrome docs, Chrome 149 release notes
Chrome on iPhone and iPadNot supportedChrome origin trials don't run on iOS, because Chrome there uses WebKitChrome origin trial troubleshooting
Microsoft EdgeOrigin trial, plus a flag for local testingTrial listed in Edge 150, released July 2, 2026. Trial expires March 30, 2027Edge 150 release notes, Edge origin trials page
FirefoxNot supported. Mozilla position: neutralPosition recorded on issue #1412, last activity August 26, 2026mozilla/standards-positions #1412
Safari (WebKit)Not supported. WebKit position: opposePosition recorded on issue #670, last activity June 17, 2026WebKit/standards-positions #670

Chrome's status record and Microsoft's trial page are the two places to check for an exact date. The sources above give no implementation plan for Firefox or Safari, so there is no version number to give for either.

Agents​

Browsers aren't the only consumers of WebMCP tools. The WebMCP community repository keeps an implementation status page that lists:

  • Brave, with experimental support in its Leo AI chat.
  • ChatGPT Desktop, listed as supported.
  • Meta Ray-Ban Display, listed as coming soon and off by default.

That page is a community list, not a vendor statement, so check each vendor's own documentation before you rely on it.

Google's own documentation is more careful. The Chrome test extensions it links to are described as separate from Gemini in Chrome, and the docs don't say that Gemini in Chrome calls WebMCP tools today.

What an origin trial means for you​

An origin trial lets one site turn on an experimental feature for its own visitors, without them changing a flag. Chrome describes the trial as limited in time, and Chrome decides later whether the feature ships to everyone. Chrome's documentation for the WebMCP trial says it is open from Chrome 149.

To use the trial on a site:

  1. Choose the trial in Chrome's list of origin trials and request a token for your origin.
  2. Add the token to every page where you want the feature. You can use a meta tag or an Origin-Trial HTTP header.
  3. Renew the token when Chrome emails you. Expired tokens are ignored.

A token is tied to one origin. A trial token from Chrome doesn't enable WebMCP in Edge, and Edge's trial doesn't enable it in Chrome. Each browser needs its own registration.

Chrome Status lists the trial's last milestone as Chrome 156. The Chrome sources here don't confirm a later extension, so check the trial's registration page for the current end date.

Try WebMCP in Chrome​

For local development, you don't need a token. Use the flag:

  1. Open chrome://flags/#enable-webmcp-testing.
  2. Set the flag to Enabled.
  3. Relaunch Chrome.

Google's guide says the flag needs Chromium 146.0.7672.0 or later.

WebMCP is gated by the tools permissions policy. It defaults to self, which allows registration in the top-level page and in same-origin iframes. A cross-origin iframe needs the allow="tools" attribute before it can register tools.

Chrome DevTools lets you debug WebMCP tools and check how the browser parses each tool's JSON Schema.

Try WebMCP in Edge​

Edge is Chromium-based. Google's guide lists the local flag as edge://flags/#enable-webmcp-testing. Edge 149 added WebMCP debugging to its DevTools.

For a live site, Microsoft's trial works differently. Register your HTTPS origin on Microsoft's origin trials page, then add the token you receive in a meta tag or the Origin-Trial HTTP header. Microsoft's docs say visitors don't need to change any edge://flags for a site that carries a valid token.

The API moved from navigator to document​

Early WebMCP code put the entry point on navigator.modelContext. The spec draft moved it to document.modelContext, because tools belong to a page, not to the browser. Use the newer name and keep a fallback to the older one:

const modelContext = document.modelContext || navigator.modelContext;

if (modelContext) {
  // Register tools...
}

The snippet comes from the Built-in AI Early Preview Program, quoted in Angular issue #68947. The sources disagree on when the old name stopped working. Chrome's 150 release notes say there are no deprecations in that release, while the Angular issue says navigator.modelContext is deprecated as of Chrome 150.0.7861.0. A Chromium commit titled "WebMCP: Remove navigator.modelContext" also exists. Keep the fallback until you confirm which Chrome version you're targeting.

What the standards bodies have said​

Both positions below come from the public issues on each browser's standards-positions repository.

  • Mozilla labelled WebMCP as neutral. In August 2026, Mozilla engineers said they support the imperative API, which lets a page register JavaScript tools, and the discussion there is about whether the declarative form, which annotates HTML forms, should also ship.
  • WebKit recorded an oppose position. The issue's labels include security, privacy, portability and consent concerns. The issue is closed, and its last activity is dated June 17, 2026.

Neither position is a shipping decision. Both browsers can still change them.

Where a WebMCP tool can run today​

The only agent that Chrome's documentation names is its own pair of test extensions. Everything else in this diagram is a browser that accepts the API.

Common misconceptions​

  • "An origin trial means it's shipped." It doesn't. Chrome describes WebMCP as a proposed web standard, and Chrome Status lists the spec as being incubated in a Community Group.
  • "A Chrome token works in Edge." Chrome's docs say a trial token won't enable features in other browsers, and Edge needs its own registration.
  • "The Chrome flag works on iPhone." Chrome's origin trials and flags don't run on iOS, where Chrome uses WebKit.
  • "Safari and Firefox will follow soon." WebKit's recorded position is oppose, and Mozilla's is neutral. Neither is a commitment to build it.

FAQ​

Can every Chrome user use WebMCP today?

No. Chrome users can reach WebMCP through a site that has joined the origin trial, or by turning on the WebMCP testing flag in chrome://flags. Chrome has not shipped it to everyone.

Does WebMCP work in Safari or Firefox?

Not in any release listed in the sources. WebKit, which powers Safari, has recorded an oppose position, and Mozilla has recorded a neutral one. Neither has an implementation to test.

Do I need a token to test WebMCP on my own computer?

No. For local testing, turn on the chrome://flags flag and relaunch Chrome. A live website needs an origin trial token.

Can I use WebMCP on Chrome for iPhone?

No. Chrome origin trials don't run on iOS, because Chrome there uses the same WebKit engine as Safari.

Should I use navigator.modelContext or document.modelContext?

Use document.modelContext, which is the name the spec moved to. Keep navigator.modelContext as a fallback until you confirm the Chrome version where it is removed.