in reply to daniel:// stenberg://

many servers will reject by default urls above 8k. But there are probably special setups out there.

Other things start to break when urls go beyond 64k. h2 may have a problem with its header handling (although headers are outside the stream's window size).

h3 will have problems with initial congestion windows where headers count for the window.

I think 64k would therefore be a limit that should not by itself pose problems.