In “The 46 Mac Apps I Actually Use and Why” (19 April 2023), I noted that the first app I installed after my Level 2 clean install was the Web browser Brave and that, just weeks later, I replaced it with what has been the most transformative app I’ve used in decades. That app is Arc by The Browser Company. Arc isn’t yet in full public release, although the company regularly invites people in from the beta waitlist.

I realize calling Arc “the most transformative app I’ve used in decades” is a bold statement that requires a lot of support. I won’t skimp on words in this article telling you why—it’s that important and requires new ways of thinking about how you work on the Web.

As the first blush of my evidence, consider that Arc has taken over the prime spot on my dual-display setup, aligned with the left edge of my right-hand 2020 iMac with 5K Retina display, which puts it smack in the center of my field of vision while also promoting it to the crisper of my two screens. I chose to relegate my email client, Mimestream, from the prime spot one email app or another has held for as long as I can remember to a secondary location: the right edge of my left-hand screen, a lower-density 27-inch Thunderbolt Display.

Arc’s reworking of the Web browser interface has caused it to feel more important to me than email. I always carefully arrange my apps on my extended desktop so I know exactly where to look when I bring one forward with an associated F-key or the macOS app switcher. So rearranging my main apps is a sea change.

Why does Arc deserve this spot? Arc’s designers have taken the Chromium engine and created a Mac-native app that improves on the standard Web browser interface in four conceptual areas: context, persistence, visibility, and refinement. Each plays a vital role in why I describe Arc as transformative. In the sections below, I’ll explain how its unique features—or at least unique combinations of features—make it stand out.

Context

Most of my time working on a Mac falls into one of three categories: Personal, TidBITS, and Finger Lakes Runners Club (abbreviated FLRC below). Long ago, I would have organized associated documents into folders. But nearly everything I do today is on the Web. In Brave, I created folders on my bookmarks bar to collect sites or pages I needed to use in each context. However, I’m a sufficiently keyboard-driven person that my most common action was to press Command-T and type enough of a bookmark name to bring up the desired page in a new tab. I pressed that combination up to hundreds of times per day. Unfortunately, by accessing everything directly, I ignored the context that those bookmark folders provided.

And context is powerful! Like many people, I’m easily distracted, so anything that takes me away from the topic and document I’m working on, even briefly (Squirrel), derails me, requiring extra effort to get back on track. Tools and techniques that reduce distraction or help me resume where I left off more quickly have outsized value. Arc leans heavily on its left-hand sidebar to assist in that role. While it has no particular name, the sidebar plays a central role in all four of Arc’s conceptual innovations.

Let’s start with two unusual Arc features that help keep me in the context within which I’m working: Spaces and Profiles.

Spaces

If the sidebar is Arc’s most prominent interface element, Spaces is the feature that leverages it more than anything else in Arc. A Space is a collection of tabs in the sidebar. It’s easy to switch between them using keyboard shortcuts (Control-1, Control-2, etc., or Command-Option-Left/Right Arrow) or by clicking little icons at the bottom of the sidebar.

You can assign each Space a color, providing an instant visual clue for what Space you’re in. For me, Personal is a green/yellow/teal gradient, TidBITS is purple, and FLRC is blue, while my fourth space—set to hold FLRC tabs for Google Docs and Google Sheets—is yellow. Each Space can also have a custom emoji or icon that identifies it in the switcher at the bottom of the sidebar.

Although the sidebar color and tab collection are generally beneficial when working in the context of a particular Space, there are times when you might want to focus exclusively on the context of the page or document at hand, temporarily dismissing other tabs. Choose View > Hide Sidebar, and the sidebar disappears until you bring it back. (Arc assigned this operation to Command-S since saving in a Web browser is infrequent.) A ring of color around the window emphasizes what Space you’re in. I usually work with the sidebar showing, but hiding it is particularly effective on my MacBook Air with Arc in full-screen mode.

Spaces has enough functionality that it let me replace a Coherence X-based site-specific browser for Google Docs. I’m usually working on only two or three documents at once for TidBITS, so those slot into my TidBITS Space. However, for the Finger Lakes Runners Club, I regularly refer to a plethora of documents, so much so that I decided to dedicate another Space to them. I could have filed them all in a folder in the FLRC Space, but my brain likes the context of “working on FLRC documents.”

Profiles

A challenging part of using a standard Web browser is the need to log into the same website using different accounts. This is a big reason many people have multiple browsers installed or use site-specific browsers. If you have work and personal Google accounts, for instance, breaking them up by browser lets you keep Gmail and Google Docs for each account separate. There’s no need to do that when you use Arc.

Arc lets you set up each Space with its own Profile. In Arc’s world, each Profile maintains its own logins, history, saved passwords, extensions, and more. For many people, that adds a lot of efficiency.

I haven’t yet created another Profile. Although I maintain multiple accounts at a number of sites, I’ve put a fair amount of setup work into ensuring that I don’t have to log out and log back in to access what I need. I use Google Docs constantly for both TidBITS and FLRC, but since the entire FLRC hierarchy is shared with my personal account, I switch to the FLRC account only to create Google Forms so they all sort together. Similarly, although I use multiple Webscorer accounts for different race timing scenarios, I have to log in each time anyway, so it’s no hardship to select the desired login from 1Password’s menu of suggestions on each login.

Persistence

Those of us who do a lot of work on the Web flip between pages that we use regularly and those we need only briefly, and it’s difficult to separate them when they’re all in near-identical tabs. Browsers need to support the property of persistence, in the sense of making regularly used pages easily accessible without allowing them to be overwhelmed by temporary pages. Current Web browsers do a mediocre job of providing persistence, contributing to our epidemic of information overload.

In the early days, the only persistence Web browsers provided came through creating bookmarks you could use to recall a website and by keeping multiple windows open. Open a new window and the previous window’s content wouldn’t change when you navigated to a new site. Heaven help you if you closed a window—or worse, all windows—and then had to restore your working environment!

Tabs offered the next big innovation, making it much easier to keep multiple pages open without the clutter of independent windows. More recently, browsers have added pinned tabs, which help reduce tab overload by letting you switch to a pinned tab rather than opening a new one to a regularly used site.

But in most browsers, tab overload is almost a given, and beyond a few pinned tabs, it’s difficult to know when you should leave a tab open because you’ll be coming back to it soon and when you should close it to keep your tabs tidy. To give credit where I was previously dubious, Safari’s tab groups—particularly with liberal use of pinned tabs—are probably a boon in this respect.

Favorites, Pinned Tabs, and Tabs

Arc’s designers have thought deeply about how to help users create appropriate levels of persistence. In the process, they eliminated bookmarks entirely, replacing them with pinned tabs. (For performance reasons, Arc keeps only recently used pinned tabs active, so unused ones don’t consume more resources than a bookmark would have.) Both are just URLs under the hood, of course, so what makes eliminating bookmarks possible is Arc’s focus on its sidebar. The sidebar has sections for three levels of persistence: Favorites, Pinned Tabs, and Today.

• Favorites: The Favorites section at the top of the sidebar holds pinned tabs for your daily-driver sites, such as email, calendar, music, social media, and task managers. The Favorites are notable only in their layout—little square tiles—and their appearance in all Spaces.
• Pinned Tabs: Below the Favorites area is the Pinned Tabs section. Anything you put in this part of a Space’s sidebar stays there permanently, so it’s a good place for pages you use regularly or would have bookmarked in the past. You can put pinned tabs in folders and even create nested folders. Arc’s approach to pinned tabs works vastly better than bookmarks because clicking one opens it in its own tab, rather than loading a new tab that mixes in with every other tab you’ve opened recently. It can take some getting used to, much like switching from a manual transmission car to an automatic—there’s no clutch, and you can get flustered trying to find it. Likewise, as a new Arc user, you might stare at a window before remembering that you can just click in the sidebar to bring up a Web page instead of searching through bookmarks.
• Today: The Today section at the bottom of the sidebar holds standard unpinned tabs that come and go, with the newest at the top. Apart from being collected at the bottom of the sidebar, they look and work like pinned tabs. The big difference is that Arc helps fight tab overload by automatically archiving unpinned tabs after a user-specified amount of time: 12 hours, 24 hours, 7 days, or 30 days. (I set mine to 7 days since I often work on an article for several days.) Closing an unpinned tab manually also archives it.

To turn a tab into a pinned tab, just drag it up into that section of the sidebar. Similarly, to make a pinned tab into a favorite, drag it into the Favorites section. Better yet, you can rename pinned tabs so they appear in your sidebar with names that make sense to you, and you can even assign them custom emoji or icons.

Arc’s pinned tabs are compelling. I’m a little embarrassed that I hadn’t used pinned tabs more in other browsers, but my brain keys off words and color, not icons like the tiny ones used by browsers with top-mounted tabs. They’re nearly invisible to me—I had to advance through tabs with a keyboard shortcut to see what was in them.

Here’s an example of how I use pinned tabs. In my TidBITS Space, I have a folder for Apple Updates containing pinned tabs for Apple’s release note pages for its operating systems. (Inside is an Old Updates folder with tabs for previous operating system release notes.) With a handful of clicks, I can populate four or five release note tabs and the Apple Security Updates page and refer to them while writing up new versions. I previously had bookmarks for these pages in Brave, but opening a bunch of new tabs at the end of a window that already contained 30 or 40 tabs didn’t make for an efficient working environment since I couldn’t easily see which tab contained which set of release notes.

Peek

There’s one more way that Arc tries to help maintain persistence to reduce tab clutter. By default, when you click a link to another site from a favorite or pinned tab, Arc opens the new site in what it calls a Peek. For this screenshot, I was reading Glenn Fleishman’s article “PowerPhotos Enables Ventura Users to Migrate iPhoto and Aperture Libraries” (21 April 2023) and clicked a link in the article to the PowerPhotos site, which Arc loaded in a Peek.

Arc creates a sort of pane to load Peeks, as you can see with the PowerPhotos site above. A Peek is more like a Quick Look window than a browser window: it doesn’t have a title bar you can drag, but it’s otherwise a full-fledged view of that site. You can do three things with a Peek:

• Read it: For many pages, you just want to read them, click around, gather some information, and move on.
• Close it: When you’re done with a page, click the X button at the top right or press Command-W to close it.
• Expand it: If something on this page requires additional attention, you can expand it into its own tab by clicking the double-headed arrow button at the top right. Pressing Command-O also works. This is like clicking a Quick Look preview to open it in an app.

What’s important about Peek is that it’s a fast way to sneak a look at a window without losing the full context of where you are and what you’re doing. As soon as you dismiss a Peek—either by closing it or turning it into a tab—you’re right back where you left off.

However, following a link in Arc on a pinned tab page to another page that falls within the s