How to change http request headers in Mozilla firefox and i.e. 7?

I need to send some HTTP headers (such as Client freshness - max-stale, min_fresh no_store, etc) in request, and clinets are Mozilla 5.0 and i.e. 8.

Can I do this without using any to开发者_开发知识库ol such as fiddler etc?

Thanks :)

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AFAIK you cannot without some external tools. Firefox has a useful extension, called Tamper Data:

https://addons.mozilla.org/en-US/firefox/addon/966/

which allows you to inspect and change headers and post parameters.