Most chaingrabs can be escaped from via neutral air like most are saying.
Then again, most chaingrabs are actually grabs that have a small window wherein they can link together and aren't actual chaingrabs (à la Marth v. Fox in Melee). For example, Pikachu has a chain on Yoshi which gets consecutive grabs, but isn't inescapable, which is what a chaingrab normally refers to.
Another example is Meta Knight's down throw when DI'd "incorrectly" (in this situation, at least), players often airdodge out of expected follow-up and get regrabbed.
King Dedede can flawlessly chaingrab if he buffers his dash. If not, you can jab out of it.
Falco's chaingrab goes up to exactly 38% before you can naturally get out; I don't know how early neutral air works in all honesty, so others who have provided their input should know.
Ike, Pikachu, and a few others like Wario have what is probably more accurately called consecutive grabs, meaning with a little horizontal positioning you should be able to escape the next one, as the window to regrab successfully isn't very large.