Source for the site is here if you're interested: https://github.com/wyattjoh/HeadersCheck
https://devcenter.heroku.com/articles/http-routing
> X-Forwarded-For > X-Forwarded-Proto > X-Forwarded-Port > X-Request-Start > X-Request-Id > Via
> X-Request-Id
"dnt": "1"
Could be a bug in Firefox, since visiting your site with Safari doesn't send the header at all (which is how it's supposed to work).
Edit: Sorry about the noise. It's not your site, and it's not Firefox. NoScript took it upon itself to set this header!
https://devcenter.heroku.com/articles/http-routing
Plus Are all Heroku-generated headers