There are extensions for Chrome and Firefox that do exactly that.

https://www.one-tab.com/

Thanks for the extensions but my idea is more around browsers treating our activity more as multiple projects that we’re working on. Like associated files, they’re associated URLs. Extensions are fool, but you’d think the browser wars would spur greater innovation in this area.

I feel that browser wars have finished and the winners are Chrome and mobile Safari. Other browsers now fight for numbers so advanced features are not really a priority.

My idea is inspired by the way IDEs keep track of a system of associated files. If browsers could manage a project file that stores tab and window data that can be saved and restored, without using any built in bookmark feature so that the project file can be saved and stored in git, then I’d be deliriously happy about this.

Safari can save all of a window's tabs to a bookmark folder, and it supports opening a whole folder as a new window.

There's no "sync", though; if you save the tabs to a folder, then open the folder as tabs, there's no link to update the folder again. Saving the new window as tabs will create another folder.

My interpretation of your comment is to literally save a list of URLs (in plaintext or html)

This plugin has "Copy all to clipboard" button which does that https://github.com/antonycourtney/tabli

That would be great if I could then open that file using a browser which would then load up those URLs.

Not exactly what you asked for, but for what it's worth Firefox will happily accept and open a list of URLs that you drag and drop from your text file into the browser. I just tried it.

Yes, you can :) https://help.vivaldi.com/article/session-management/

What’s your OS? You can do that on macOS via AppleScript. Works on Safari, Chrome, and possibly Vivaldi. Won’t work on Firefox because they don’t support AppleScript.

There is an extension that does exactly that: https://www.gettoby.com/

Edge does that. You can "set aside" the tabs you currently have open. You can have multiple set of tabs "set aside"

You can do that with stock Chrome, no extensions needed. Bookmarks->Bookmark all, then a bookmark folder has "Open all".

Was hoping to save to a file, (call it a project file) that can then be subject to git versioning, retrieved later and suddenly it’s all back where it was, without using bookmarks.

I wonder if there is an API that you could access to get that? I'd like that feature too.

OneTab chphlpgkkbolifaimnlloiipkdnihall

Tabs Backup & Restore dehocbglhkaogiljpihicakmlockmlgd

in Vivaldi: File > Save Open Tabs as Session

And it will be saved in a directory named `Sessions` inside your profile directory. You can then copy this file and use in another Vivaldi instance.