Very practical Rated 5 out of 5 stars

Very practical, easy to use and efficient. The URL pattern matching is a huge plus.

Rated 5 out of 5 stars

It's very useful!

Spent some minutes to see how easy to use is this extension.

You edit your conf in a textarea as key:value pair. One per line. The key is the header name and value is the header value.

Values can be evaluations of javascript expressions.


Rated 4 out of 5 stars

This addon is very useful to modify headers. At first it is a bit unexpected to just write the rules in the sidebar, but that turns out to be very effective.

I'm removing one star because currently, I need to switch it off and on again to work.

Rated 5 out of 5 stars

Functionally it works as expected - is easy to use (once you read the blurb at the bottom of the addon).

Seems to work when modify headers didn't.

I don't understand end users.. Rated 5 out of 5 stars

to add a little context:
* I'm a programmer
* I'm planning to write a little addon that will modify HTTP response headers
* before starting to write any code, I wanted to survey what other addons already exist. Either one that will serve my need, and I can use. Or one that has somewhat similar functionality that I can use as a starting point for making changes.

what I found:
* no addons currently exist to modify response headers. there are a few available that will modify request headers. of these..
** "modify-headers" is incredibly popular, and it's complete crap
** this addon ("header-tool") is beautifully written.. in both its coding style, as well as its functionality. Sure, there's a few things that I would've done slightly differently. But this tool is 99.999% complete. And for all the effort that this programmer ("Lorenzo Pavesi") has put into its development since 2011 (periodic refactoring, new features, general maintenance).. he has 11 reviews with an average rating of only 3 stars. Really??! This addon is awesome! And (for what it's worth), I just wanted to say so. Great job, Lorenzo!


Thanks Warren, you give me new interest on the project with your beautiful review. And i´m going to commit myself to implement the "modify HTTP response headers" :) any suggestion is always welcome

Sloppy Rated 1 out of 5 stars

The documentation, and even the add-on itself, are rife with typos. The sidebar can only be brought up with the dropdown menus at the top, which, being hidden by default in modern FF builds, many users will not think to check and might not know how to access.

Most damning, it does not do what I, for one, expected it to do after reading the description. I wanted to capture HTTP headers in plaintext as I sent them, and then be able to modify them; if it was meant to capture headers, then that feature is not working.

Not working Rated 1 out of 5 stars

Doesn't install in latest Seamonkey :(

Great stuff Rated 5 out of 5 stars

I was used to Modify Headers, then Header Tool came..Simple and useful.. Thumbs up!

This review is for a previous version of the add-on ( 

Very useful Rated 5 out of 5 stars

I just discovered Header Tool today and found it extremely convenient to use. There could be some enhancements (like for examples access to other header and maybe form data) but in its current form it is much more useful than Modify Headers, which I used before.

Best thing is the possibility to set headers based on the URL accessed, which Modify Headers does not offer.

This review is for a previous version of the add-on ( 


I really appreciate your comment and if you have comment on how improve it just let me know on support site :

Rated 4 out of 5 stars

really useful tool for Web developer and troubleshooter. Easy to activate and de-activate any header, just adding a "#" (not so handy the more famous Modify headers).
It just misses a profile handling...

This review is for a previous version of the add-on ( 

Unusable Rated 1 out of 5 stars

Description says, it should be easier than modify headers - i say it is unusable - I didn't get a simple modify of User-Agent working...

This review is for a previous version of the add-on ( 

you are probably looking 4 this

Rated 1 out of 5 stars

needs better documentation - seems broken

the editor is very difficult to use - it inserts many spaces/indents at random when inserting a line break

i wrongly assumed you could set and save headers on a per-site basis like Mason - nope

no toolbar button

This review is for a previous version of the add-on ( 

Hi man,
the regexp feature was planned and will be available since version 0.3.6 (currently in sandbox). The documentation you can get is at the first page of . Where is also available the new "@regexp" syntax.

Rated 5 out of 5 stars

One of the most useful add-on nowadays. I suggest to install it because it makes web development a lot easier.

This review is for a previous version of the add-on ( 

Unclear Rated 1 out of 5 stars

No option to work on headers, nowhere to write any JS, no help. Unuseful

This review is for a previous version of the add-on ( 

Too simple probably

Jef which options you need? the syntax is probably too simple
header:${ jscode }
and comments starts with a # .

this plugin is intended to be used for modify the headers, and do it fine.
before say it's unuseful please read the documentation ( 4 line in the description ).

Rated 5 out of 5 stars

This is my favorite plugin for the mobile development. I really love the geeky interface.

This review is for a previous version of the add-on ( 

Give us example,please Rated 4 out of 5 stars

How to do it? Just write Content-disposition : nothing ? I don't know anything about JS. Can you explain how to remove header on example "" site? Thanks.

This review is for a previous version of the add-on (  This user has a previous review of this add-on.

Hi i've done a quick read to, should be enough to put an empty value for the header you can put Content-Disposition : ${" "} . let me know if its works for you or please open a ticket with the feature description you need on and i'll implement it better in the next release, in the ticket put a single HTTP GET with the expected result.