What a session manager is, and what it will not fix

"Session manager" names three unrelated kinds of software, and the search results mix them together. AWS Session Manager is a tool in AWS Systems Manager that opens a shell on a server without SSH keys or open inbound ports. A desktop session manager on Linux saves which applications were running at logout and starts them again at login. A browser session manager is an extension that saves your open windows and tabs so you can restore them later. If you arrived here after a browser crash wiped thirty tabs, you want the third. If you arrived from an AWS console, you want the first. This page explains each one briefly, then spends most of its time on the browser kind, because that is where the gap between what people expect and what the tool does is widest.

Which session manager you are looking for

A quick way to tell them apart is to ask what is being saved and restored.

Name	Saves or controls	Where it runs	Typical reader
AWS Systems Manager Session Manager	Shell access to managed servers, with logs	AWS console or AWS CLI	Engineers running servers
Desktop (X) session manager	Which applications and windows were open	Linux desktop environments	Linux desktop users
Browser session manager	Open windows, tabs and their order	Browser extension	Anyone with many tabs

The rest of the page takes them in that order. Skip to the browser section if servers are not your concern.

AWS Session Manager: shell access without SSH keys

The AWS documentation describes Session Manager as a fully managed tool in AWS Systems Manager for managing EC2 instances, edge devices, on-premises servers and virtual machines, through either a browser-based shell or the AWS CLI. Its central promise is secure access without opening inbound ports, maintaining bastion hosts or managing SSH keys.

For anyone used to SSH, the shift is in where trust lives. Instead of a key on each server or a certificate authority signing user keys, access is granted and revoked with IAM policies, in one place. AWS lists the other main capabilities as port forwarding from a port on the server to a local port, support for Windows, Linux and macOS nodes from the same tool, and logging of session activity for audit requirements.

Set side by side with plain SSH, the differences look like this, based on the same AWS page:

	SSH	AWS Session Manager
Inbound port on the server	Port 22 open, or a bastion host	No inbound port needed
Who may connect	Keys or certificates on each server	IAM policies, managed in one place
Starting a session	An SSH client and the right key	One click in the Systems Manager or EC2 console, or the AWS CLI
Audit trail	Whatever the server logs	CloudTrail for API calls, plus optional session logs to S3 or CloudWatch Logs
Notification of sessions	Not built in	EventBridge rules with SNS when a session starts or ends

One exception is easy to miss. AWS notes that session logging is not available for sessions that connect through port forwarding or SSH, because SSH encrypts the session data inside the connection and Session Manager acts only as a tunnel. Teams that adopt Session Manager for its audit trail and then keep using SSH through it lose exactly the feature they came for.

To start a session from the command line on a Mac, two pieces are needed. The plugin installation page states that the Session Manager plugin must be installed locally, that it requires AWS CLI version 1.16.12 or later, and that plugin version 1.2.764.0 or later is required because earlier versions will soon stop being supported. Running session-manager-plugin --version shows what is installed.

Cost changed recently. According to the Systems Manager pricing page, checked on October 18, 2026, Session Manager has no additional charge on Amazon EC2 instances, with limits that may apply. For hybrid and multicloud nodes, meaning servers outside EC2, usage was not billed during a transition period from June 30 to September 30, 2026. From September 30, 2026, pay-as-you-go pricing of $0.05 per session applies on those nodes. AWS's own example works out 200 hybrid nodes with one session each in a month at $10 for Session Manager.

Desktop session managers on Linux

The second meaning comes from the Linux and Unix desktop. In the X Window System, as the Wikipedia article on X session managers puts it, a session manager can save and restore the current state of a set of running applications, including the window manager. The visible effect is logging out and finding the same windows in the same state when logging back in. To make that work, the session manager records which applications were running at logout and starts them again at login.

The window content is the hard part. Restoring a window's contents, not just reopening the program, requires the application itself to save its state when the session manager asks and to load it again on start. The protocol that defines that conversation is the X Session Management Protocol, XSMP. Applications that cannot store their state can still be part of a session, but they come back empty. Sessions can also be saved at any time, not only at logout, and a user can keep several named sessions and choose one to load.

This is why a Reddit thread titled "what does a session manager do" on a Linux forum has nothing to do with AWS or browser tabs. On a Mac the equivalent behavior is built into macOS. Apple's guide to shutting down a Mac describes the "Reopen windows when logging back in" option in the Shut Down dialog, which brings app windows back at the next login, so there is no separate program to install.

What a browser session actually contains

A browser session, in the sense a session manager extension uses, is a snapshot of structure: which windows are open, which tabs are in each, in what order, and, in newer tools, which tab groups they belong to. Tab Session Manager, one of the most used, lists its features on its Firefox listing as saving and restoring windows and tabs, naming and tagging sessions, saving automatically when a window closes or at regular intervals, importing and exporting sessions, cloud sync, and support for tab groups. On October 18, 2026 that listing showed 175,176 users and a 4.2 rating from 1,244 reviews.

What a session does not contain matters as much:

• Sign-in state. Whether you are still logged in after a restore depends on the cookies the browser kept, not on the session file. If the cookies were cleared, every restored tab opens at a login page.
• Unsaved work. Text typed into a form or an editor that had not been saved is not part of the snapshot.
• Which account a tab was using. A restored Gmail tab opens with whichever account the browser currently has signed in.

Before installing anything, check what the browser already does. Chrome's On startup setting has a Continue where you left off option, under Settings, On startup, that reopens the pages you had open when you quit. Firefox's release notes for version 137 note that tab groups are always saved and that a closed group can be reopened later. For many people, those two settings are the whole answer.

How long an extension can be relied on

An extension that holds months of saved sessions is only useful while it keeps working, and browser platform changes can end that. Chrome's Manifest V2 support timeline is the recent example. Manifest V2 extensions were disabled for all Chrome users with Chrome 138 on July 24, 2025, with no way to turn them back on, and on August 31, 2026 all remaining Manifest V2 extensions were removed from the Chrome Web Store. Existing installs on Chrome 138 or earlier keep running but receive no updates and cannot be reinstalled if removed.

Any session manager that was not migrated is gone from Chrome. Tab Session Manager was. Its version history on the Firefox listing records version 7.0.0 as the migration from Manifest V2 to V3, version 7.2.0 as adding tab group saving in Firefox, and 7.4.0 as the current version, updated on July 18, 2026. Its source is public on GitHub under the MPL-2.0 license.

Four checks protect your saved sessions whichever extension you choose:

1. Confirm it has been updated within the last year and uses Manifest V3.
2. Use its export feature on a schedule and keep the file somewhere outside the browser.
3. Know where the data lives. Local storage disappears with the browser profile, while cloud sync depends on the extension's own service continuing.
4. Test a restore once, before you need it. Save a small session, close its window, and restore it, so the first time you rely on the tool is not the day after a crash.

What a session manager will not fix

People often install a session manager hoping it will solve one of four other problems. It solves none of them directly.

Too many tabs. Saving forty tabs and restoring them later puts the same forty tabs back. It helps you close them with less worry, which is useful, but the clutter returns on restore.

Memory use. Restored tabs load again and use memory again. Some extensions restore tabs unloaded until clicked, which delays the cost rather than removing it.

Several accounts on one service. A session file does not know that one Gmail tab was a client account and another was personal. Keeping two accounts signed in at once needs separate cookie storage, such as browser profiles or Firefox containers.

Losing the always-open apps. If what keeps disappearing after a crash is mail, chat and a calendar, the issue is that they live as ordinary tabs among everything else. A session manager restores them as ordinary tabs again.

That last case is where a different tool fits. App aggregation browsers on macOS keep each web app in a fixed place in a sidebar, each with its own cookie container, grouped into workspaces you switch between. The app's place does not depend on a saved tab list, and switching workspaces does not sign you out of anything. The workspaces page explains how that separation works, and the Ferdium comparison shows an open source tool built on the same idea.

What to change first

If you lost tabs in a browser crash, turn on Continue where you left off in Chrome, or rely on Firefox's saved tab groups, before installing anything. If you need named sessions you can come back to weeks later, choose an extension that uses Manifest V3 and was updated recently, and export its data regularly. If what keeps going missing is a set of always-open web apps with several accounts, give them a fixed home in an app aggregation browser such as SpaceDeck.