I downloaded some .dae files, and they open up fine in programs, but I noticed that the files aren’t in their normal XML format when I open them in TextEdit on my Mac. Instead, the text is all compressed like a ZIP file. Is there such thing as compressed dae files? The word compressed is also in the file name. I can probably upload one of the models if anyone wants to take a look at it

Also, is there a way to create these compressed dae files? An app that I use only works with these type of Collada files.

ZAE (.zae) is COLLADA in ZIP format. It’s part of the standard. Otherwise, I don’t know, could be a binary XML file, or something like that. If a program’s fallback mechanism can figure out the format, then it will open it as COLLADA by way of the xmlns field in the COLLADA element.