Enhance multitasking extensions with the new Tabs Split View API

Google released the Split View API for Chrome extensions starting in Chrome 155, letting developers programmatically detect, create, and manage the browser's built-in side-by-side tab layouts. The API, developed with Mozilla and other vendors in the WebExtensions Community Group, is part of the browser.tabs namespace and requires no permissions, adding a splitViewId property to Tab objects plus browser.tabs.createSplit, browser.tabs.unsplit, and a splitWithTabId parameter on browser.tabs.create. Chrome 145 introduced native Split View in February 2026, but extensions previously could not control the layouts and relied on workarounds such as resizing native windows, iframes, or side panels.

Earlier this year in February 2026, Chrome 145 introduced the native Split View https://blog.google/products-and-platforms/products/chrome/chrome-productivity-improvements/ which provides users with the ability to view and manage tabs side-by-side within the same window, removing the need to rely on third-party tools to manage separate OS windows. While users can manually add and remove tabs from a split view through browser controls, it was not possible for developers to programmatically control these new tabs layouts in Chrome extensions. We're excited to announce the new Split View API, available starting in Chrome 155 Developed in close collaboration with Mozilla and other browser vendors in the WebExtensions Community Group, this new API allows extensions to detect, create, and manage built-in split views. Demo How it works Previously, extensions building side-by-side experiences relied on brittle workarounds like resizing multiple native windows, embedding pages in <iframe elements, or using side panels. Now, the new Split View API integrates directly with Chrome's Tabs API https://developer.chrome.com/docs/extensions/reference/api/tabs to unlock new tabs layout management capabilities. Manifest permissions The Split View API is part of the browser.tabs namespace, and they don't require any permissions to use. Identifying split views Every Tab object contains a splitViewId property https://developer.chrome.com/docs/extensions/reference/api/tabs :%7E:text=the%20sessions%20API.-,splitViewId,-number%C2%A0optional . If the tab is part of a split view, it shares a unique identifier with its paired tab; otherwise, the splitViewId defaults to -1. js // Querying all split views in the current windows const tabs = await browser.tabs.query { currentWindow: true } ; const splitViews = tabs.map tab = tab.splitViewId .filter splitViewId = splitViewId == -1 ; General constraints In order for two tabs to be able to join a split view, they must meet the following requirements: 1. Tabs must be or created adjacent to each other. 2. Tabs must not be already in a split view. 3. Tabs must have the same pinned , windowId , and groupId state. Conversely, when two tabs are unsplit, they will retain the same pinned , windowId , groupId states along with the relative positioning to each other. Creating split views There are two methods by which an extension can create a new split view: 1. Create a new tab that will split with an existing tab using the new splitWithTabId parameter in browser.tabs.create . 2. Pair two existing tabs with the new browser.tabs.createSplit method. Examples You can create a new tab using splitWithTabId to split with an existing tab. await browser.tabs.create {splitWithTabId: existingTab.id} ; By default, the new tab will be created to the right of the existing tab. To create a new tab to the left of the existing tab, set the index as that tab's index: await browser.tabs.create {splitWithTabId: existingTab.id, index: existingTab.index} ; You can also create a new split view by pairing two existing tabs. await browser.tabs.createSplit existingTab1.id, existingTab2.id ; Unsplitting split views To separate a split view into two independent tabs, an extension can use the new browser.tabs.unsplit method. js const splitViewId = browser.tabs.createSplit tab1.id, tab2.id ; // Unsplitting the split view into two independent tabs await browser.tabs.unsplit splitViewId ; Learn more We hope this new capability will supercharge more productive workflows for your extensions. To start building extensions with split view capabilities, check out the Tabs API https://developer.chrome.com/docs/extensions/reference/api/tabs documentation. If you have any questions or need help with the Split View API, visit the Chromium extensions https://groups.google.com/a/chromium.org/g/chromium-extensions?e=48417069 Google Group. Happy splitting