Chrome 155 Split View API Lets Extensions Open Side-by-Side Tabs

Chrome got native Split View in Chrome 145 back in February 2026, but until now only you could put tabs side by side, using the browser controls. Extensions had no way to do it. That changes in Chrome 155 with a new Split View API, announced on the Chrome for Developers blog.

What the Split View API does

Full control: the API lets extensions detect, create and manage built-in split views. Google built it in close collaboration with Mozilla and other browser vendors in the WebExtensions Community Group.

No permission prompts: the API lives inside the browser.tabs namespace and does not need any manifest permissions. As PiunikaWeb points out, that means fewer scary permission warnings for users.

Goodbye workarounds: before this, extensions that wanted side-by-side layouts had to resize several native windows, embed pages in frames, or use side panels. Google calls those workarounds brittle.

How it works for developers

Rules for pairing: the two tabs must sit next to each other, must not already be in a split view, and must share the same pinned, window and tab group state. When you unsplit them, they keep those states and their positions.

Our take: this is a small change you will not see right away, but it should lead to better tab and productivity extensions. Because Mozilla helped build it, extension makers have a better shot at tools that work the same way across browsers.