Google-speakr

[phranque]

apparently there's a new UA related to Google Go that started appearing as early as september from what i've seen.
crawls have been reported from IPs in the 64.233 66.102 and 66.249 ranges

it isn't yet documented on G's user agent page [support.google.com] but it was confirmed by danny sullivan [twitter.com]:

That's an useragent used when Google Go fetches a page to make sure it has the most up-to-date information before it translates it to read aloud. We'll see about adding documentation. More info here:
Make Google read it [blog.google]

[not2easy]

I had noticed that Google sends a bot from 66.102.128.0/20 for verification of "new" domains in GSC. I had previously blocked that range on one domain, it used to be registered to ADD2NET-DOT-COM about 5 years ago.

[engine]

There are reports of an agent google-Read-Aloud
Have you seen it in your logs?

The Google User Agent page seems to have disappeared.

[phranque]

perhaps not a complete list but there is this:
Google Crawlers [support.google.com]

[phranque]

there is this:

i just realized that's the same user agent page i linked to in the the OP...

[lucy24]

i just realized that's the same

The first version explicitly says hl=en, while the second version is silent. If the latter means it defaults to your system language, that may or may not be an advantage. (Do they auto-translate, or only check whether the page exists in your language?)

:: detour to check, after remembering that my own system language is one Google doesn’t know ::

You get a 404 either way. And also if you Google “google user-agent” and click on the link (interestingly, #2 in the SERP).

Oh, if only we were allowed to insert ROFL emoticons.

Here [developers.whatismybrowser.com] (#1 on SERP) is quite a long list, though it isn’t arranged in a very useful way.

Edit: For the sake of scrupulous accuracy, I guess I should replace “you” with “I” in all of the above.