Even though we now have over a decade of e-commerce history under our belts, credit card processing is still one of the most stone-knives-and-bearskins primitive aspects of web app development. It seems like a lot of trouble and arcana just to move money from buyer to seller, an action that at its essence is as old as civilization itself.

Making matters worse for the developer is the sad state of documentation on credit card processing. It’s often unintelligible, written as if it was given as an unwanted task to an intern who couldn’t care less. Sometimes it’s outright wrong.

Enter the folks from the Freckle time-tracking web application: Amy Hoy, Thomas Fuchs and Dieter Komendera. They decided to do a good deed an create a guide titled Jump Start Credit Card Processing, a 15-page PDF guide that explains credit card processing in a manner that’s not just comprehensible, but fun to read. Here’s a sample page:

Among the things explained in this guide are:

• The credit card processing life cycle
• Key industry terms and actions
• JavaScript code for validating & detecting card types
• Code samples for the ActiveMerchant Ruby module
• A “getting started” checklist & account information

Best of all, this guide is available for download absolutely free of charge. If you’re new to the world of e-commerce apps and want to make sense of credit card processing, I strongly recommend Jump Start Credit Card Processing. Grab it from the Jump Start site.

The article Casual Cryptography for Web Developers is probably the nicest, most concise explanation of some of the important crypto principles and practices that web developers will need. Whether you are new to web development, need a refresher or are just curious about the fundamentals, this is one of the best starter articles I’ve seen.