Is there an internet equivalent in the Star Wars galaxy?

Question

Is there a canon source that describes a galaxy-wide computer network in the Star Wars galaxy?

Does it mention how big the internet is in the galaxy?

Answer 1

In Disney Canon? Not really, no.

The Holonet was a communication network that transmitted holograms around the Empire. In Tarkin, the holonet is restricted to the Empire only, and in various episodes of Rebels the plot surrounds taking over broadcast stations to send Rebel propaganda, which makes the Holonet look like cable television.

But the Holonet is also responsible for ship to ship hologrammatic transmissions; the holograms in Empire Strikes Back are Holonet transmissions; the transmission of Darth Sidius in The Phantom Menace also also via Holonet.

(In Legends, it's explained that the Holonet operates in hyperspace, which is why communication is so fast. Subspace communications are slower, and "mail" only goes the speed of whatever ship it's on.)

Now, we do see droids communicating with comlinks occasionally, so it's not beyond the pale to imagine that droids could connect to each other via comlinks to communicate.

Limiting to Disney Canon, though, computers are treated as monolithic mainframes with huge databases, where data has to be retrieved either online (via connected terminals) or transferred via physical storage (Rogue One). Data transfer is handled by a "sneakernet," with data updates carried by ship to other mainframes, which update their local databases (kinda like usenet newsgroups before the Internet).

Answer 2

So I arrived here after having read a duplicate question on the same subject, and I'm in full agreement with the answer above. On the same subject, this is from the Encyclopedia of Science Fiction entry on The Force Awakens.

"Star Wars is best articulated as fantasy not sf: despite the galaxy-spanning Space Opera arena in which it takes place; despite a Galactic Empire at stake, in which a dynastic quarrel is repurposed as a war between Good and Evil; and despite the operatic Spaceships and Weapons (though Mecha are absent this time round, and there are no Scientists available to supply upgrades). Underneath these gestures towards sf, it is all fantasy. Vast energies are generated by wands. Sketchily urbanized planets dissolve as though daylight had struck a Vampire. As before, the Robots on view are pets who fixate like familiars upon their various owners. No computers or cellphones or Internet can be seen; if they exist, they are tapestry. There are no cities left to smash flat. There are no populations".

The key assertion here is "No computers or cellphones or Internet can be seen; if they exist, they are tapestry."