You only need to read the news about how issuers are raising rates dramatically (MSN Money article) and changing terms without warning (USA TODAY article) to understand why a credit card ranking tool is one of the first offerings on Jemstep’s pre-launch alpha site.

Fortunately, if you rely on Jemstep, you’ll stay one step ahead of the fine print.

Let’s see how Jemstep works its magic, with a short walkthrough of this Live Ranking tool for credit cards. (The Jemstep alpha also includes a ranking tool for mutual funds, which we’ll discuss in our next post.)

If you are an alpha user, log in to Jemstep now. (If you’re not an alpha user, you can register for the Jemstep beta version here.)

Select the Credit Card tab, and then take a look at My Credit Card Preferences. There are five sections for you to enter preferences, with more dozens of criteria overall-everything from your credit score to preferred balance transfer features to the types of rewards you’re interested in.

Don’t be daunted by the scope of possible preferences though. Enter only what you want, and watch Jemstep dynamically tailor its rankings for you. You can narrow the field by limiting your rankings to a particular institution, or experiment with different usage scenarios, such as how much of your balance you pay off every month.

When you’re satisfied with your preferences, your custom-built list of credit card rankings is ready to explore. Start with your #1-it’s the one that best suits your needs. You can get details about a card, add it to your profile, and even apply for the card.

If you want information about a specific card you already own, or one you’re considering, enter the name of the card under My Stuff. Jemstep will rank the card and show you how it matches up to the competition.

To top it off, when you add a card to your LifeData profile, Jemstep continually monitors details about the card, keeping track of all those “gotchas,” such as new fees and interest rate changes, that have caught a lot of people by surprise.