HTTP header parser & converter
Paste raw headers as copied from browser DevTools (Name: value per line), the -H flags of a curl command, or a JSON object. Request lines, status lines and HTTP/2 pseudo-headers (:method, :path…) are skipped.
Frequently asked questions
How do I copy request headers from Chrome?
Open DevTools → Network, click a request, and in the Headers tab tick “Raw” next to Request Headers, then copy.
What happens to duplicate headers?
In JSON / fetch / Python output, repeated headers are combined with “, ”. The curl output keeps each one as a separate -H flag.
Why are some headers flagged for fetch()?
Browsers don't let scripts set certain headers such as Host, Cookie, Content-Length or Connection; they are listed in a comment instead.
Can I modify headers in the browser instead?
Yes — PlainHeaders adds, changes or removes request and response headers on the sites you choose.