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Re: Freezing the User-Agent header

From: Daniel Stenberg via curl-library <>
Date: Mon, 24 Feb 2020 21:04:59 +0100 (CET)

On Mon, 24 Feb 2020, Tim Rühsen via curl-library wrote:

> as freezing the User-Agent header is currently a thing, I would like to ask
> the curl community about their opinions.
> The reason for freezing is to reveal less privacy data and make
> fingerprinting harder.

Those are part of the reasons we reduced the curl user-agent many years ago
[1]. I don't think we're in the same situation as the crazy headers of the
browsers. The curl user-agent header as of right now is a very small privacy

But also, I don't think the version number in the header is very useful other
than in a subset of debugging cases so I wouldn't be upset if we would remove
that as well...

I've not personally planned on reducing it further. Also note that libcurl
itself has no default user-agent header at all.

> Omitting User-Agent is not an issue as random web sites use User-Agent
> sniffing (often in wrong ways, but that is a different issue).

The entire idea of this freeze is primarily a browser concept since they want
to offer users APIs and other ways to get the info that sites currently are
trying to figure out by sniffing the user-agent. Other HTTP clients will not
be able to offer those APIs as easily and neither do we use the browsers'
crazy user-agent headers.

[1] =

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Received on 2020-02-24