What are FFRKI or Creeper? o_o
FFRKI is a tool that, coincidentally, I wrote when I first started playing this game like 2 years ago. It basically injects itself in between your device and the game's server and watches all the data as it comes across. Then it displays a bunch of statistics and stuff, and back in the day it would send drop information to a centralized database. So for farming a specific item you enter the dungeon, and as soon as you enter it sees what is going to drop for you and displays it.
Most of its usefulness is obsolete however, because it was really mainly used for collecting orb drop information to min-max farming efficiency. You could search the database, filter, find best drop rates for certain items, etc. With the current and future dailies, the optimal answer for orb farming is just "do the highest stamina daily / orbfest". Plus, it's pretty difficult to set up FFRKI due to the way it basically does a Man in the Middle on your internet connection.
Creeper is something that someone else created a few months ago. It solves the same problem but in a different way. It's FAR easier to set up, but it has its own drawback, which could be a deal killer for some people.
Basically you connect your phone to a proxy like Fiddler, then due some steps to determine your "session id". You then go to the aforementioned website, enter your session id, email address, and phone number, and press a button. At this point you can turn off the proxy. Even leave your house or change networks. You then enter a dungeon, and as soon as you enter, it sends you an SMS and email with your drops.
The drawback though, which is the deal killer for some, is that it impersonates you to the DeNa servers. Every second or two, it constructs a message that says "hey, give me the latest information", sends it to DeNa pretending to be your device, and uses the response to figure out if anything dropped for you. To some this could be a privacy invasion and, unlike FFRKI, is actually detectable should DeNa care.