Sidekickブラウザ alternatives: what you can drop

The search for a Sidekickブラウザ replacement returns a long list, and the entries have almost nothing in common. Vertical tab browsers. Browsers that give each web app its own window. Guides that say a Chrome profile plus a tab group extension is enough. The list feels impossible to rank because the ranking question is wrong. Sidekick bundled several unrelated features into one app, and most people leaned on two of them. Once those two are named, most of the list disappears on its own.

What happened, and what can still be checked

The public record is short. In May 2025, Perplexity acquired the team behind Sidekick. Perplexity shipped Comet, its own browser, for macOS and Windows on July 9, 2025, and opened it to free download in October 2025. Sidekick itself sunset on August 3, 2025.

One part of this is still verifiable from any machine. A request to the old domain comes back as a permanent redirect, and the destination is a different product:

$ curl -sI https://www.meetsidekick.com/
HTTP/2 301
location: https://comet.perplexity.ai

The redirect applies to deeper paths as well, including the old pricing page. That matters more than it looks. Any article that quotes a specific Sidekick plan price can no longer be checked against the source, because the source is not reachable. Treat those numbers as history rather than as a benchmark for pricing a replacement.

The redirect destination is also worth reading carefully. Comet is described as a browser built around an assistant that carries out multi step tasks. It is not a rename of Sidekick, and it does not inherit Sidekick's sidebar and session model by default. Landing there and assuming the migration is done is the most common wrong turn.

Six features, two of which are hard to replace

Sidekick combined six capabilities that have little to do with each other.

Session separation. Two accounts on the same service, both logged in, side by side.

Sidebar apps. Gmail, Slack, Notion pinned to the left edge instead of living in the tab strip.

Spaces. A switchable grouping of what is open, usually per project or per client.

Search across open apps. One entry point that reaches into what is loaded.

Split view. Two panes on one screen.

Ad and tracker blocking. Protection that shipped turned on.

The reason the replacement list looks incoherent is that each candidate product covers a different subset. A browser with a beautiful vertical sidebar does nothing for account separation. A product with strong spaces may still share one login across all of them.

There is a cheap way to find out which of the six mattered. Think back over the last working week. Clicking icons at the left edge to move around points to sidebar apps. Repeatedly signing out and back in on one service points to session separation. Switching spaces only a few times a month means spaces were never load bearing.

The split between replaceable and not

Feature used	How it gets replaced	Effort
Session separation	A browser built around isolated containers, or several browser profiles	High
Sidebar apps	A browser that keeps each web app in its own window, or native clients	Medium
Spaces	Tab groups, or the workspace feature in a mainstream browser	Low
Search across apps	Each service's own search, plus Spotlight	Low
Split view	Split Screen in macOS, or two windows side by side	Low
Ad and tracker blocking	An extension, or blocking at the network level	Low

Everything in the low row shares one property: it can be added later, to almost any browser, in a few minutes. That is exactly why those rows should not drive the choice. A candidate that advertises tab groups and a built in blocker is advertising things the reader can get anywhere.

The top two rows behave differently. Session separation is a decision about how a browser stores cookies, and no extension retrofits it. Sidebar behaviour is not a cosmetic preference either, because it determines whether a notification arrives with an icon that identifies which account it belongs to. If neither of the top two rows applies, the honest answer is that no replacement purchase is needed at all.

The candidates fall into four groups

Sorted by how they are built rather than by name, the replacement list collapses into four groups.

The first is a mainstream browser plus profiles. It costs nothing, it handles simultaneous logins, and it is already installed. Its weakness shows up once several profile windows are open at the same time, because nothing on screen reliably says which one is in front.

The second is a browser with vertical tabs or workspaces. These are strong on visual order, and some of them are genuinely pleasant to live in. The catch is that the workspace may be a label rather than a container, which is covered in the next section.

The third is a browser that keeps each web app in its own window. Separation happens per app and per account rather than per tab, so notifications arrive with an identifying icon and each app has a fixed address. The switching cost is the highest of the four, and it is the only group that satisfies both of the hard rows at once.

The fourth is going back to native clients. Mail and chat as desktop applications, with the browser left to handle research and everything occasional. Tab counts drop sharply. The limits are that multi account support in native clients varies by vendor, and that each application updates on its own schedule.

Which group fits follows directly from the count above. Someone who never needed session separation and picks the third group pays for capability that goes unused. Someone with daily multi account work who stays in the first group keeps mistaking one window for another. Neither outcome is about product quality.

The word workspace means two different things

Among the candidates, the biggest source of confusion is a single word. Products use workspace, space, or project for two structurally different things.

The first kind is a label. It groups what is open so the screen looks tidy, and switching between labels does not change who is signed in. The second kind is a container. It holds its own cookies and storage, so the same service can be open under two accounts at once.

Feature lists rarely make the distinction, so the fastest way through is a test rather than a comparison table. During a trial, put the same service into two separate spaces and sign in with different accounts. If the first session drops, it is a label. If both survive, it is a container. That single test sorts the candidate list faster than reading a dozen reviews, and it is the one property that cannot be changed later.

For products in the container category, the shape of that unit is the thing worth understanding before committing. What is isolated and what stays shared is set out under Features, and the reasoning for grouping apps per project or per client rather than per service is described under Workspaces. Whether the services in daily use are covered is listed on Supported apps.

What actually has to move

Migration feels heavy mostly because the list of things to carry is never written down. In practice it holds three items.

Bookmarks move through an HTML export and import, supported by every mainstream browser. The export takes a minute. The slow part is deciding what to leave behind, which is optional and can be skipped.

The list of pinned apps cannot be exported, so it gets written by hand. Write the icons from the left edge in order, then mark each one daily, weekly, or monthly. Anything marked monthly does not need a permanent slot. This step alone usually shortens the list, which in turn changes which pricing tier is relevant.

Logged in sessions do not move at all. Every service needs a fresh sign in, so the two factor method has to be at hand before starting. Where an employer restricts which applications may reach a workspace, one service should be tested a week ahead rather than on migration day. That single test is where migrations stall.

Saved passwords are a fourth item only if they live inside the browser. If they do, moving them to something independent of any browser is worth doing during this migration rather than during the next one.

Measure for a week before paying anything

Before picking from a shortlist, spend a week without a replacement at all. The point is measurement, not endurance. With the bundle gone, only the parts that were genuinely carrying weight will make themselves felt.

Three counts are enough. How many times a sign out and sign in happened on the same service. How many times a window or tab hunt happened to reach a known screen. How many notifications were noticed late. Tally marks on paper are fine.

A high first count means session separation is the requirement, and the visual candidates can be removed from the list. A high second count means fixed placement is the requirement, which points to per app windows. A high third count usually means the notification settings themselves are misconfigured, in which case no browser change fixes it, and macOS notification settings and Focus modes deserve a look first.

If all three counts come back low, the outcome is a saved subscription. The remaining work is pruning bookmarks and pinned apps, and it costs nothing.

There is a second reason to run the week before committing. Memory tends to overstate friction, because the annoying moments are the ones that get remembered. Counting them usually produces a smaller number than expected, and occasionally a much larger one, and either result changes which group above is worth paying for. The counts also give a baseline to compare against after switching, which turns a vague impression of improvement into something checkable.

Where the trade offs actually sit

Once the requirement is one of the top two rows, the comparison narrows to four columns: how multiple accounts are handled, which operating systems are supported, where settings and sign in state are stored, and what the pricing is charged per. Long feature grids beyond those four columns rarely change the decision.

Differences between products in this category are set out one property at a time under Compared with Wavebox, Compared with Shift, and Compared with Ferdium, while the specific mapping against Sidekick's model is covered under Compared with Sidekick. Charging models are on Pricing, and the questions that come up before switching are collected on the FAQ.

What to change first

Write out the left edge icon list before opening any comparison page, and mark each one daily, weekly, or monthly. If three or fewer come back daily and no service appears twice, the fix is fewer pinned apps rather than a new browser. If five or more come back daily and the same service appears under two accounts, the unit of separation needs to move from tabs to windows, which is the problem SpaceDeck is built around.