I'll admit that PDF IMG's availability has been shit for a while and I apologize. Many of the downtimes have been caused by people uploading PDF files and then using PDF IMG's DPI settings to massively increase the output size, which caused the Java virtual machine to eat up all available memory and more or less exit.
Today, I've rolled out a new build that attempts to solve this problem by limiting the in-memory size of a converted image to 250 MB and also re-using previously generated image buffers. This new limit will only affect around 0.02 % of all visitors.
I hope this will make PDF IMG much more stable and reliable.
The downside is that, when you convert PDF files to images now, your output images may be smaller than than you had in mind.
In other news, PDF IMG has been upgraded to Bootstrap 2.3.1. Below, you can see the old and the new looks.
I've also ported some new technology from the new media.io over to PDF IMG which will increase the website's performance.