Why use a preview version of a browser?

A preview browser is a second install that gets new code before the stable release does. You use it to try a web platform feature, or to see if the next release will break a site, while the browser you work in stays where it is.

Chrome

Chrome Canary is the build with the newest changes. Chrome has four channels. Checked in November 2026, this is the pace:

Stable and Beta moved from a 4-week milestone to a 2-week one starting with Chrome 153, on 8 September 2026. Canary and Dev kept their pace. Enterprises can stay on Extended Stable, a new milestone every 8 weeks, with security fixes in between.

The Canary name comes from the canaries used in coal mines. Wiktionary defines a canary as “something which warns of the coming of greater danger or trouble”. Google lands changes there with little testing. A Canary build can crash, or fail on a site that worked yesterday. A daily build also means the fix can land the next day.

A feature you find in Canary is not a promise that Stable will get it. Some experiments stop there. Beta is the channel for “will this hit people on the next release”. Canary is the one for “does this API exist in a build yet”.

Open chrome://version and read the channel. Canary, Dev, Beta, and Stable are separate apps, each with its own profile. A broken Canary does not delete the bookmarks in Stable.

Chrome Canary exists on Android as well as desktop.

Firefox

Firefox Nightly is Firefox’s Canary. Nightly builds about every 12 hours from the main branch. Nightly and Beta exist for Android too.

Every 2 weeks that code moves to Beta. Beta then ships about three times a week while it stabilizes. Firefox Developer Edition is a desktop-only build of the Beta branch, with defaults aimed at web development. Release is what everyone else runs. Firefox moved Release to a 2-week cycle starting with Firefox 155, on 1 September 2026.

Nightly keeps its own profile, so it does not share Release’s bookmarks and extensions unless you point it at that profile. about:support shows the update channel and the version.

Safari

Safari ships with macOS and iOS, so there is no daily channel. Safari Technology Preview is a separate macOS app running a newer WebKit than the Safari in the current system. Apple updates it every few weeks through the Mac App Store, and you run it next to Safari.

The wait is longer than Chrome’s two weeks. A feature can sit in Technology Preview across several releases before the next macOS update picks it up for regular Safari. There is no Technology Preview on iPhone. For iOS you wait on a system beta.

Edge

Edge is Chromium, with its own builds. Canary, Dev, and Beta are separate apps next to Stable. Canary updates daily, Dev weekly, and Beta and Stable about every two weeks, so a pass in Chrome Canary still leaves Edge to check on its own.

The feature can be in the build and still be off

Landing in Canary does not mean the feature is switched on. Chrome turns many experiments on for a fraction of users, and you can flip them at chrome://flags. Firefox puts the same kind of switch in about:config. If a demo works only after you enable a flag, people on Stable do not have that demo.

Back then I used Canary to test Intl.RelativeTimeFormat and Intl.ListFormat. Intl.RelativeTimeFormat shipped in the ES2020 Intl spec, and Intl.ListFormat in ES2021. Both have since shipped in every major browser. See JavaScript internationalization for how to use them.

The preview tells you the API runs on your machine. The people opening your site are on Stable, often a version back, and often on a phone. Detect the feature, or wait until the browsers you support have shipped it.

How I would use them

I would keep Stable as the browser I sign in with. I would install Beta next to it and open the site there when release notes mention a change that could break layout or a web API the site uses.

I would install Canary or Nightly when I am trying one feature that is not in Beta yet. I would not make either one the daily browser. A bad morning build takes that session with it, and a site tested only there was tested on a browser your users don’t run.

For the browser you live in, see Chrome alternatives compared.

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