Home

---

HTTP Header Mangler

HTTP Header Mangler is a Firefox add-on which inserts HTTP headers on a per host basis.

Matching hosts is done with either simple strings or regular expressions.

Rules can have multiple headers apply to multiple hosts, or simply insert a single header for a single host.

How to write a rules file

A rule is made up of contiguous lines of text.

Each line of a rule defines one of two things:

• a simple string or regular expression for matching a host
• an HTTP header expressed as Name=Value

To qualify as a rule and not be ignored, at least one of each of the above must be present.

All headers defined in a rule will apply to each and every matching host for that same rule.

A newline acts as a delimiter for rules.

Comments are defined as lines starting with the # sign, and are ignored.

Whitespace at the beginning and the end of a line is ignored. Consequently, indentation is ignored. Whitespace at the beginning and the end of a header name or value is also ignored, meaning it will be removed from said name or value.

Example rules file

example.com
.*regexp\d+
# This is a comment.
X-Forwarded-For=10.11.12.13

	# Indentation is allowed.
	foobar
# Formatting with whitespace is allowed.
X-Forwarded-For    =    100.101.102.103
User-Agent         =    Mozilla/3.0 (X11; I; AIX 2)

# Here's an incomplete rule, which will be ignored.
Accept-Language=en-US,en;q=0.5