The site looks great. However, I agree with apsurd. If you first let users play around, it shouldn't take long until they're hooked and much more eager to sign up.
there's a little problem - we have autosave. so, there's not a single button after you make a new chart where we could ask to login. I strongly agree that it is aggressive that we ask to authorize this way. what's better:
a) descriptive images / screenshots on front page (aka "learn more")
b) add a save button (then ask for login), unless it's pressed no data is saved.
Thanks for elaborating, that makes sense. Since I noticed in another one of your other comments that you're planning on a freemium model, I think Option A is a good enough starting point. Once you get the ball rolling, it would be interesting to test both options to see which actually converts better.
I may be the only person with this question, but if I use Twitter to sign up, will it have any impact on my timeline (like an automatic "I just signed up for Infogr.am" tweet)?
thanks for advices. regarding twitter - no, never, no tweets. by the way, this is something someone could communicate to twitter - they actually say what permissions you give us (read your timeline + know whom you follow = to tell if your friends are here)