One example is qutebrowser: https://qutebrowser.org/doc/help/settings.html#content.headers.custom https://qutebrowser.org/doc/help/settings.html#content.heade.

One example is qutebrowser: https://qutebrowser.org/doc/help/settings.html#content.headers.custom https://qutebrowser.org/doc/help/settings.html#content.heade... I assume other developer-centric browsers have similar options.