Chrome side panel: what belongs in it and what belongs in a window

A narrow column opens on the right, holding bookmarks or a reading list or an extension, and the first question is usually whether it can be closed or moved. The more interesting question comes a week later. If a panel can hold a reference document, a translation tool, or a chat window, how much of a working day can be moved into it, and where does that stop paying off.

The answer is decided by one property of the feature that is easy to miss: the panel is a single slot, and everything that wants to appear there takes turns. That constraint, rather than any preference about layout, determines what is worth putting in it.

What Chrome puts there, and what that reveals

The default occupants are documented as a short list. The side panel on a computer holds the reading list, bookmarks, history, and Google Lens among other items. Those four have something in common that is worth stating out loud: none of them is a place where work gets done. They are ways of finding, choosing, or capturing something.

The reading list collects pages to return to. Bookmarks expose a saved hierarchy without giving up the current tab. History lets a previous page be found without pushing the current one aside. Google Lens acts on a selection from the page already open. Every one is a lookup, and lookups are short.

That pattern is a reasonable guide for anything added later. The panel suits tasks measured in seconds where the main content stays in view: checking a term, pulling a link, glancing at a value. It suits tasks measured in minutes less well, and tasks that run all day least of all, because the slot will be wanted by something else before the day is over.

A narrow column next to the page is a place to look things up, not a second desk. Holding that distinction in mind makes the rest of the decisions straightforward.

Four controls, and one of them matters more than the rest

The mechanics are small. The panel is resized by dragging its edge. It is closed from the Close button at its top right. Its side is set under Settings and then Appearance, where a Side panel section chooses which edge it opens from. On a wide display, moving it to the left keeps the page text where the eye expects it.

Pinning is the control that changes daily behavior. Chrome allows five panels to be pinned individually: Google Lens, the reading list, bookmarks, history, and reading mode. Each is pinned from the menu entry that opens it, by selecting the option to pin it to the toolbar, after which its icon sits to the left of the profile avatar. Unpinning uses the matching option, or a right-click on the icon.

Pinning is worth restraint. Every icon added to the toolbar makes the others slower to find, which means the honest test is whether a panel gets opened several times a day. Anything opened weekly is better reached through the menu, where it costs nothing to leave.

Width deserves one note. Opening the panel takes space from the page, and most sites change their layout below a certain width, stacking what had been side by side. Widening the panel to read a table more comfortably can push the page itself into its narrow layout, which makes the page harder to read rather than easier. Position and width are set separately, so a combination that works can be chosen once per use and left alone.

One other piece of naming causes avoidable confusion. A search result page that opens an article alongside a column of related results is sometimes also called a side panel, and closing it has no effect on the browser feature described here, because the two come from different places. The browser panel is part of the window and persists until it is closed. The search column belongs to the page that produced it and returns with the next search. Whether it comes back after being dismissed is the quickest way to tell which of the two is on screen.

Reading mode occupies the slot for a different reason

Among the pinnable panels, reading mode is the outlier. It is opened from the menu under More tools, and it moves the text of the current page into the panel, where font, font size, color theme, line height, and letter spacing can all be adjusted.

The scope of those adjustments is the part that surprises people, and the documentation is explicit about it:

These settings only apply to the text you want to read in the side panel. They won't apply to any other content in Chrome or to general websites. Source: support.google.com

So reading mode is not a way to impose a comfortable color scheme across the web. It is a way to read one article without the images and video around it, with typography that can be tuned for that article alone.

This gives a clean rule for what kind of content suits the panel. Prose survives being moved into a narrow column and stripped of layout. Anything where position carries meaning, such as a dashboard, a spreadsheet, or a diagram, does not. A specification with numbered clauses reads fine in a panel. The same specification presented as a table of comparisons does not.

Extension panels follow different rules

Anything beyond the built-in list arrives as an extension, and the rules there are set by an API rather than by settings. The documentation states its availability as Chrome 114 and above on Manifest V3, with a sidePanel permission declared in the extension manifest. An extension that shows the same panel everywhere points the side_panel key's default_path at a page inside itself.

Three properties of that API explain most of the inconsistency people notice between one panel and another:

The side panel remains open when navigating between tabs (if set to do so). It can be available only on specific websites. As an extension page, side panels have access to all Chrome APIs. Source: developer.chrome.com

The parenthetical is doing real work. Staying open across tabs is a choice the extension makes, so one panel persists while another closes the moment the active tab changes. Site restriction is also a choice: when a site is not enabled, the panel closes and the extension stops appearing in the side panel list at all, which reads as a bug from the outside and is documented behavior from the inside.

Opening behavior varies for the same reason. An extension can allow its toolbar icon to open the panel, and from Chrome 116 it can also open the panel in response to a user action on its own page or in a content script. That is why some panels respond to the toolbar and others only to a button inside a page.

For anyone evaluating a panel extension, those three points form the checklist. Does it stay open across tabs, is it limited to certain sites, and is the installed Chrome recent enough. A panel that never appears in the list is often answered by the second or third question rather than by reinstalling.

One slot, chosen from a list

The single most consequential fact about the feature is that there is one panel area. What appears in it is selected from a list, which the extension documentation refers to directly when it describes an extension dropping out of the side panel drop-down menu. Two things cannot occupy it at once.

That turns the question of what to put there into a ranking problem rather than a layout problem.

Task	Side panel	Separate window
Finding a page in bookmarks or history	Good fit, opened and closed in seconds	Unnecessary
Reading a long article while writing notes	Good fit, the article goes in the panel	Either works
Checking a glossary while writing code	Works if there is only one reference	Better once there are two
Watching a chat channel all day	Poor fit, anything else displaces it	Good fit
Answering mail	Poor fit, the column is too narrow	Good fit
Switching between two accounts on one service	Poor fit, the account follows the profile	Good fit

The line runs through a single question: how many things need to stay visible at once. At one, the panel is sufficient and pinning it is worthwhile. At two, they compete for the slot, and the switching that pinning was supposed to remove comes back in a different form.

There is a second limit that is easy to overlook. A panel showing a signed-in service shows the account tied to the current profile, because the panel lives inside the browser window rather than beside it. Someone using the same service under a work account and a personal account sees only one of them in the panel, and reaching the other means changing windows anyway.

Ranking the candidates is quicker than it sounds, and it can be done on paper in a minute. List everything that would ideally be visible while working, then mark each entry as either a lookup that ends in seconds or a presence that has to stay. The lookups can share the slot happily, because they are never wanted at the same moment. The entries marked as presences are the ones in conflict, and their count is the number the panel cannot satisfy. A list with four presences on it will not be fixed by a better extension or a wider column, and knowing that before installing anything saves an afternoon of trying panels in turn.

What belongs in a window instead

The panel was built to keep a lookup within reach. A working day made of mail, chat, a ticket queue, and two admin consoles is four or five things that all need to stay visible, which is one slot short by any arrangement of pinning.

At that point the useful change is not a better panel but a different unit. Giving each web app its own window, inside one browser designed to hold them, means each one keeps its own space and its own signed-in session, and moving between them is a matter of looking rather than selecting from a list. The way that division is organized is described in Workspaces, and the services that can be treated this way are listed in Supported apps. For a comparison against other tools that take the same approach, the differences are laid out in Compared with Shift.

Framed that way, the two features stop competing. The side panel stays useful for exactly what its default occupants suggest: bookmarks, history, a reading list, a lens on the current page. The applications that need to be present all day sit elsewhere, and neither one is asked to do the other's job.

What to change first

Write down everything that needs to stay visible during a working day. If the list has one entry, pin it as a side panel and stop there. If it has three or four, the panel is the wrong container for them, and SpaceDeck is built to give each one a window of its own.