Nope. All image processing is done in your browser. That said, if you decide to use the mobile link feature, the image will be temporarily stored for 15 minutes on the server so you can reload it on your phone to more easily share with apps such as Instagram.
Wait, what does the mobile link do?
I got really annoyed of having to take my photos (on my computer), upload them to a shared service, download them to my phone, and reupload to an app such as Instagram. Here, I can queue up the collage here and easily scan the QR code on my phone to access the work done on my computer. (If you're using this on a phone, don't worry about this feature.)
How do I adjust the zoom / position of a photo in a collage cell?
Click (or hold) and drag inside the cell to shift the photo. Use the middle mouse wheel / pinch gesture to zoom in and out.
How big is the resulting collage?
3000 px on the longer side.
What images can I upload into the collage maker?
ONLY IMAGES YOU HAVE THE RIGHT TO USE SHOULD BE PUT HERE. Good fricking lord I can't believe this has to be spelled out, but here we are:
Do NOT upload content that is considered illegal in the United States (where this website is hosted), or in the jurisdiction you, the user, are in.
Do NOT upload content that infringes any copyright, trademark, or other intellectual property right.
Do NOT upload content that contains malware, exploits, or files designed to damage or compromise systems.
Do NOT upload content that is used for fraud, phishing, or impersonation.
Do NOT upload content that contains non-consensual intimate imagery or content that violates another person's privacy rights.
Do NOT spam the server.