How can I check the size of an uploaded file to ktor? Checked the documentation and searched here but surprised I couldn’t find something

I'm interested in the same thing.

You can get the number of bytes from the

Content-Length

header (if it's available) before receiving the body.

That's a good first step, however the client could lie about it. If the client lies, will Ktor trust the value?

What do you mean by trusting the value?