Most popular Base64 strings

Here I’ll try to collect a list of most popular Base64 strings and provide a brief description for each of them. I will gather them together from different sources, including search queries and strings processed by the Base64 decoder. I know what your next question is, so no, I don’t store all Base64 strings on my server. To gather most popular Base64 strings I’m storing the MD5 hash and the user IP. If there are more than 100 different IPs decoding the same Base64 string the app will save it as plain text. Periodically I’m reviewing these strings and I’m publishing them if there is really something interesting.

• JVBERi0xLjMNCiXi...cxNA0KJSVFT0YNCg
  This Base64 string is a is a small demonstration PDF file used in the Virtual Mechanics tutorials. Please leave a comment if you know any additional details about it.
  
  
• R0lGODlhAQABAIAA...AAABAAEAAAIBRAA7
  This Base64 string is a 1x1 full transparent GIF image. As a rule, one pixel transparent images are used by web developers to track visitors or control white space.
  
  
• SSdtIGtpbGxpbmcg...b3VzIG11c2hyb29t
  This Base64 string is the result of encoding a phrase from the hip-hop song “Ice Ice Baby” written by American rapper Vanilla Ice. It seems that this Bae64 string first started being used by the Cryptopals Crypto Challenges.
  
  
• iVBORw0KGgoAAAAN...AAAAAElFTkSuQmCC
  This Base64 string is a PNG image (mostly in blue tones) with a resolution of 16×16. Perhaps it is used as a “close icon” or to display the letter “X”.