> Where did you hear of them?
I no longer recall, I’ve been using them for something like two decades.
> But there's no screenshots or example usages, and it's not obvious to me how it works.
See SnippetsLab for a good example of a snippets manager.
https://www.renfei.org/snippets-lab/
> I guess it's meant to be used as a VS Code extension. It might work as a standalone app but it would be a little unwieldy.
I prefer it as a standalone app. I don’t use VSCode nor would I want integration with my text editor. Snippet managers generally have ways of being invoked from anywhere, or you can type a few characters and have them replace the text, or you can search them from launchers like Alfred.
https://www.alfredapp.com
https://alfred.app/workflows/renfei/snippetslab/