It's right
here, the description gives the 5V/3A output.
I saw that Blunty posted a video recommending 15V/2.6A chargers like the Razer for the Switch, I'm guessing that's where the confusion today is coming from. I like the guy's previous videos about the Switch but, while I haven't watched this one yet, I feel like it's misleading too many people based on speculation. I'm guessing that he came to that conclusion but we've seen that the back of the Switch specified 15V/2.6A input, but you gotta understand that's the MAXIMUM the Switch can take. It's entirely possible the Switch will charge faster with 15V, but at this point there's evidence that 5V chargers DO work to charge while playing games (albeit slowly) from both Rarez and Digital Foundry, as well as a handful of anecdotal reports over the past few days from previews. There's really only one or two reports of the Switch having issues with battery banks, and those are anecdotal and lacking much actual details. I'd rather take the word of the Rarez video and Digital Foundry article which both clearly state they were using a 5V3A USB-C port and got a charge while playing out of it.
Fortunately, it won't be much longer before all this confusion clears up. When I pickup my Switch tomorrow night I'll test it out with my 5V RAVpower battery bank right away to see if it charges the battery while playing Zelda and will report back about it.