Google's URL shortening service (one of them), with possibly some browser-plugin support for typing go/<your-link-id> tied to your own organization's short links (maybe this concept is known as go links). They also offered you a subdomain, e.g go.yourdomain.com/your-link-id.

I tried pretty hard, but couldn't find a public URL for this EOL announcement. To be fair, even coverage of this service's existence is a bit scarce. All I have is this email (below screenshot) and I'm pretty sure it's because I have http://go.xs.fi/ (it's operated by Google) with links added by me previously, here's one public link: http://go.xs.fi/hp_procurve_2626

Here's a screenshot of the UI:

I couldn't find date when this service was launched (the Medium article I linked to mentions "around 2010" which coincides with some of my links' "last access" being in 2013 and one link I had was to a document originating in 2010 but I can't remember when I created the short link), so I'll leave the date blank in my PR.

I also have to link the URL here because there's not much info on this service. But it was a service that Google offered for me and it annoys me that the "forever" URLs will be breaking.