たって・とも: the difference
たってN2
Meaning
Even if, Even though, No matter how
Past papers
Tested 4 times in past papers
Example
パーティーにはピザじゃなくたってかまわないよね。
It doesn't have to be pizza at the party, right?
ともN2
Meaning
Even if, No matter
Past papers
Tested 2 times in past papers
Example
どんなことになろうとも、国家が破産するのはまずありえない。
Whatever happens, it is very unlikely that a nation would go bankrupt.
How to tell them apart
「たって」: talk between friends; never use it in formal papers or business e-mails.
「ても」: the standard form, fine in speech and writing.
「とも」: literary and old-fashioned; tone of an oath or philosophy.