I'm looking for fonts, available from Google Webfonts (ideally) or Typekit, that would look similar to Avenir Next Pro, specifically, Bold and Demi:
Any similar-looking fonts, with good cross-browser rendering?
Nunito is really quite different to Avenir - the letters are quite rounded.
I've done some serious work on this for a client and found the Google font Lato is virtually indistinguishable from Avenir - you can literally put two words in the two fonts next to each other and not tell the difference.
If you really want to use a Google Font, I highly suggest using NUNITO. It has 3 styles: Book, Normal, and Bold. Here is a sample comparison between Book 300 and Avenir: https://web.archive.org/web/20140415053621/http://joelcrawfordsmith.com/new/font/avenir The sentence length is a perfect match and x-height is great. Its only fault is that the ascenders and descenders are a tiny bit shorter.
Lato is also a comparable Google font:
FYI, for the lighter AvenirNext faces, don't overlook Ideal Sans. They are virtually identical. I haven't compared the heavier weights, but for the lighter, this is my go-to. Yes, the lower-case g is different, but otherwise, it's pretty good. I realize I'm necro-posting, but for anyone else that comes along:
I have found Prompt to be very close to Avenir Next Pro within google fonts.
You can check the comparison here
Avenir is available for the web at fonts.com
I believe that Sofia Pro Light from Font Squirrel is a close match.
The question is by now three years old, but I really feel I should mention League Spartan from the League of Movable Type. It's not from Google Fonts, but it's free and Open Source:
The League has given only the most well-made, free & open-source, @font-face ready fonts
Nunito is an excellent alternative to Avenir. The ascenders are slightly higher in Avenir but even the most persnickety designer would have a hard time telling them apart. It can be found at http://www.google.com/webfonts/specimen/Nunito it has 3 styles created by Vernon Adams
Nunito (Book 300)
I've been hunting for a good replacement for this. Open Sans, Source Sans Pro, and all the other popular sans-serif fonts on Google Fonts are really nothing like Avenir Next. Avenir Next is a thin font. I used this filtering on Google fonts to find similar thin sans-serif fonts. I found two: Heebo and Yantramanav. Using these with the Thin or Light style gets me pretty close to Avenir Next.
I came across Open Sans, and it seems like the uppercase J is the only letter that's obviously different.
I would recommend Futura as an alternative to Avenir or Avenir Next