Yes third party parsers are against the ToS, but as they don't contact the server or modify data, just read the data stored locally SE cannot track their usage. You won't get banned as long as you don't talk about it, or talk about it out of the game.

For example if you are parsing and discussing the information ingame (party/fc/ls chat etc) and someone decides to report you, yes they can take action against your account because there is server side evidence of you saying you are parsing which, for now, means you are using third party tools. However if you use voice chat to discuss parsing results there is no evidence you have used anything. SE don't accept hearsay as evidence to take action against accounts, just hard evidence.