Firefox Search Engine Cautions, Recommendations

Firefox Search Engine Monetization

See the revision history at the end of this document for a list of changes.

Introduction

This tutorial covers various aspects of search engines for Firefox (or a derivative thereof) including sanitizing the default search engine plugins and how to add new search engines. For a list of alternative search engines, see Alternative Search Engines That Respect Your Privacy.

When ‘free’ software isn’t

I suggest reading The Mozilla Monster as a primer.

Have you ever wondered how Mozilla get paid by the mega-monopolies like Google? Simple: When you use the default search engine plugins that are packaged with the browser, parameters similar to these are added to your search query:

client=firefox
name="appid" value="ff"
name="hspart" value="mozilla"

These parameters inform the search engine that you’re using a Firefox/Mozilla product and that’s all it takes for Mozilla to rake in the dough. If you do not wish to participate in these affiliate schemes and/or value your privacy, read on.

Types of search engines

The two basic types of search engines are meta search engines and search indexes and it is important to understand the difference. Google, Yahoo and Bing for example, use software robots called “crawlers” to discover and index web content. In other words these companies actively seek out updated and fresh content to store in their databases so it’s ready for you to find. On the other hand, meta search engines do not typically index the web and instead rely primarily upon third parties like the aforementioned to provide their search results and therefore when you use these so-called “alternative” search engines, such as DuckDuckGo, Startpage, Searx, etc., you are still subject to the filter bubbles and censorship that is employed by the corporate giants. That said, the ethical meta search engines still make a great deal of sense from a privacy perspective since one can avoid being tracked by the big companies directly. Understand though that they are not true alternatives as they are often described, but rather proxies that insulate you from the privacy thrashing search engine giants. These alternative search engines are also subject to local laws, such as secret surveillance requests issued by a government.

Indexing the web and storing the massive amount of data that results is an incredibly expensive proposition which requires a massive amount of infrastructure and this is why the much smaller meta search companies like DuckDuckGo, Startpage and others rely heavily upon corporations like Google. There is a better solution than meta search engines, one which both respects your privacy and is censorship resistant. Ever hear of a peer-to-peer distributed search engine? Imagine a free, open-source, decentralized search engine where the web index is distributed among millions of personal computers like yours, each storing a piece of the whole. This is what the developers behind YaCy have done with their search engine and i think it’s a great way to move forward.

Adding search engines to Firefox

Possibly the easiest way to mitigate risks to your anonymity posed by the default Firefox search engines is to simply disable all of them and use alternatives. One of my favorites is the open source and highly customizable Searx meta search engine which you can host on your own server if you like, or you can use any one of a number of Searx instances hosted by others. Like DuckDuckGo, Startpage and others, Searx is not an index and so it does not crawl the web like Google, however the big difference between Searx and most of the other meta search engines is that it is capable of pulling results from many other indexes including Google, Yahoo, Bing, Wikipedia, DuckDuckGo, Startpage, Qwant and many more, as well as decentralized peer-to-peer indexes such as YaCy. The Searx interface also offers a lot of configuration options for fine-tuning your search results, including the ability to select exactly what combinations of search engines you want to use for a particular type of search, of which there are currently 10.

One easy way to add Searx to Firefox is to locate a hosted instance which you like and which is preferably close to you geographically, then from the Firefox search bar menu, simply click the “Add” menu item. While searx.me is the original instance of Searx as provided by the developers, it is best not to use it because it can become overloaded. The Searx developers cannot afford to have too many people using their instance without your help and so they will disable it at times in order to promote other Searx instances. That said, a potential pitfall of using a third party instance is that the server may be logging traffic, such as IP addresses, location, etc., so you’ll have to decide whether you can trust them.

Most other search engines can be added to Firefox in the same way as described above, but there are additional methods also. The Mycroft Project hosts tens of thousands of preconfigured search engine plugins for a variety of web browsers, the top 100 of which are listed here. They also have a form for writing your own search plugins. Although it is not possible to review the code from the main listing of search plugins, you can use their submission form to do so by mousing over the plugin name to reveal its numeric ID, then filling in that ID in their submission form page. Because Mozilla changed they way search engine plugins are added to Firefox, you’ll need the Add Search Engine from Mycroft Project add-on to install the search plugins from Mycroft.

Another easy way to add a custom search engine to Firefox is with the Add custom search engine add-on by Tom Schuster. This add-on allows more control over the above methods, including the ability to define the website icon path or base64 code (a binary-to-text encoding scheme that encodes the site icon in text form). A great on-line resource for converting an icon to base64 code is the Base64 Encoder utility which can accept the icon URL or an uploaded file.

The Search Engines Helper add-on by ‘Soufiane Sakhi’ is another easy way to add search plugins to Firefox, as well as import and export your search plugins. Like the Add custom search engine add-on, this one also allows using a URL or base64 code for the icon.

My preferred method of adding and editing search engine plugins is with the mozlz4-edit Firefox add-on by ‘serj_kzv’. This slick extension allows you to edit the search.json.mozlz4 search plugin file directly from within Firefox, though a browser restart is necessary before the changes are realized. It is in this file that Firefox stores the code for all of the search engine plugins. The add-on works for both the newer compressed version of the file with the *.mozlz4 extension, as well as the older, uncompressed version (search.json). Regardless of how you add search plugins, the mozlz4-edit add-on is a handy tool to have for editing the search.json.mozlz4 file because you can use it to decompress, edit, sanitize, recompress and then save it, overwriting the old one (make sure to make a backup first). See the Sanitizing the default search engine plugins section below before you do this though.

Sanitizing the default search engine plugins

If you would rather avoid the hassle of manually sanitizing the default Firefox search engine plugins, see the Pre-sanitized search plugins section below.

Sanitizing manually

If you choose to use the default search engine plugins provided by Mozilla, you may want to sanitize them in order to circumvent some risks to your privacy, however you should be aware that doing so will not prevent tracking or other privacy risks when using the default search engine plugins. If you insist on using the default search engines, you should use something like the ClearURLs add-on which at least strips the tracking parameters from the search engine result links. You should also disable JavaScript for the search engine web page if possible.

If you have already added custom search engines to Firefox, then the first thing to do before you start hacking is to create a copy of search.json.mozlz4 and work with the copy, reason being that if you mess up, Firefox will will delete all of your search plugins and restore only the default ones. If you don’t want to see or use the default ones, disable them in the search preferences of Firefox rather than removing them from the plugin file.

To edit the search.json.mozlz4 file you first need to decompress it. There’s at least a few utilities available that will handle this, but i would suggest using the mozlz4-edit Firefox add-on by ‘serj_kzv’ since it is very easy to use and it provides a basic code editor with syntax highlighting. Simply click the ‘mozlz4-edit’ toolbar button to load the add-on. Next, click the ‘Open file’ button and navigate to your Firefox profile folder and select the search.json.mozlz4 file. In the following example we will sanitize the Google search plugin which should give you an idea of what to look for when you decide to sanitize the other default search plugins. As of Firefox version 62, here’s what the default code for the Google search plugin looks like, though without the lengthy base64 icon string which i removed for brevity:

{
    "_name": "Google",
    "_shortName": "google-2018",
    "_loadPath": "jar:[app]/omni.ja!/google-2018.xml",
    "description": "Google Search",
    "__searchForm": null,
    "_iconURL": "[base64 icon code removed]",
    "_metaData": {
        "order": 5
    },
    "_urls": [
        {
            "template": "https://www.google.com/complete/search?client=firefox&q={searchTerms}",
            "rels": [],
            "resultDomain": "www.google.com",
            "type": "application/x-suggestions+json",
            "params": []
        },
        {
            "template": "https://www.google.com/search",
            "rels": [
                "searchform"
            ],
            "resultDomain": "www.google.com",
            "params": [
                {
                    "name": "q",
                    "value": "{searchTerms}"
                },
                {
                    "name": "ie",
                    "value": "utf-8"
                },
                {
                    "name": "oe",
                    "value": "utf-8"
                },
                {
                    "name": "client",
                    "value": "firefox-b-1-ab",
                    "purpose": "keyword"
                },
                {
                    "name": "client",
                    "value": "firefox-b-1",
                    "purpose": "searchbar"
                }
            ]
        }
    ],
    "queryCharset": "UTF-8"
},

In the above code you will notice the string firefox is used several times. This is how Google knows you’re using Firefox and thus how Mozilla gets paid when you use the Google search plugin, though it may not be the only way Google knows you’re using Firefox. To sanitize the code,we simply want to remove any mention of firefox, but we first need to duplicate that block of code, else Firefox will restore the default plugins as previously mentioned. To duplicate the code, highlight the entire Google block of code beginning with the opening bracket ( { ) and ending with the closing bracket and comma ( }, ). Note that you must eliminate the comma if you paste the copy as the last one in the "engines": section. You will also need to add a comma after the closing bracket for the plugin code block above your copy if that code was the last one in the "engines": section. If this is confusing, just know that each block of code for every search plugin must end with a closing bracket followed by a comma ( }, ), except for the last one where there can be no comma.

After removing the parameters which identify Firefox as our browser, here’s what our sanitized copy of the Google plugin looks like:

{
    "_name": "[s] Google",
    "_shortName": "google-2018",
    "_loadPath": "jar:[app]/omni.ja!/google-2018.xml",
    "description": "Google Search",
    "__searchForm": null,
    "_iconURL": "[base64 icon code removed]",
    "_metaData": {
        "order": 5
    },
    "_urls": [
        {
            "template": "https://www.google.com/complete/search?q={searchTerms}",
            "rels": [],
            "resultDomain": "www.google.com",
            "type": "application/x-suggestions+json",
            "params": []
        },
        {
            "template": "https://www.google.com/search",
            "rels": [
                "searchform"
            ],
            "resultDomain": "www.google.com",
            "params": [
                {
                    "name": "q",
                    "value": "{searchTerms}"
                },
                {
                    "name": "ie",
                    "value": "utf-8"
                },
                {
                    "name": "oe",
                    "value": "utf-8"
                }
            ]
        }
    ],
    "queryCharset": "UTF-8"
}

You can simply copy the above code and paste it as the last search plugin as described earlier, just be careful to add a comma to the last closing bracket of the search plugin above it as described earlier.

Here are the changes we made:

This…

    "_name": "Google",

became this…

    "_name": "[s] Google",

There’s two reasons for the above change, 1) you can’t have two search plugins with the same name and 2) prefixing Google with the [s] let’s us know that this is the sanitized version of the Google search plugin.

Next, this…

"template": "https://www.google.com/complete/search?client=firefox&q={searchTerms}",

became this…

"template": "https://www.google.com/complete/search?q={searchTerms}",

and this…

                },
                {
                    "name": "client",
                    "value": "firefox-b-1-ab",
                    "purpose": "keyword"
                },
                {
                    "name": "client",
                    "value": "firefox-b-1",
                    "purpose": "searchbar"
                },

was removed entirely to become this…

                }

Notice that we needed to remove the comma after the last closing }of the parameter code block since it is now the last block of code in the "params": section.

Finally, the last closing bracket for the Google plugin code block which looked like this…

},

had the comma removed since we pasted the new Google plugin code block at the end of the "engine": section.

Sanitizing the remaining search plugins is accomplished in a similar way as above; you want to look for and remove any instances of ‘firefox’, or ‘mozilla’, or sometimes just ‘moz’ or ‘ff’. Once you’ve sanitized the default search plugins, just use the ‘mozlz4-edit’ add-on to save your changes as a ‘mozlz4’ file, overwriting your existing search.json.mozlz4 file. If you restart Firefox and all your customizations are missing, then there was likely a syntax error in your edits.

Download pre-sanitized search plugins

If you do not want to sanitize the default search engine plugins yourself you can download my pre-sanitized copy which contains a search.json.mozlz4 file that should work for Firefox version 57 and up (“up” meaning until the next time the M@M’s (Morons@Mozilla) decide to break everything again). The download contains the default engines which come with Firefox version 62, plus the sanitized versions of them, plus all of the engines i personally use. All in all there’s over 40 search engine plugins which you can edit or disable as you see fit. Many are already disabled since i only use them occasionally, so be sure to adjust as necessary in your Firefox Search preferences.

Download: ff-search-plugs.zip

Install: Backup your existing search.json.mozlz4 file, then extract the archive and copy search.json.mozlz4 file to your Firefox profile directory and restart Firefox.

Sanitizing the prefs.js search engine preferences

Another item you should check is whether prefs.js in your Firefox profile directory contains any browser.search.param preferences. To sanitize these, load about:config in the browser address bar and enter browser.search.param in the search field. If none are found, great, but at the time i originally wrote this article there were two preferences found; browser.search.param.yahoo-fr and browser.search.param.yahoo-fr-ja. The default values may be different in your case, but in mine they were data:text/plain,browser.search.param.yahoo-fr=linuxmint and an empty string, respectively. What you should do is create a custom user.js file to store your modified preferences if you don’t already have one, then copy the following code to it:

user_pref("browser.search.param.yahoo-fr", ""); // sanitize Yahoo
user_pref("browser.search.param.yahoo-fr-ja", ""); // sanitize Yahoo

Removing Firefox system add-ons

Mozilla packages some system add-ons with Firefox, installs them without your permission and doesn’t provide the user with any convenient means to remove or disable them. These system add-ons have been used for very controversial purposes in the past. To remove them, see the ‘System add-ons‘ section of the Firefox Configuration Guide for Privacy Freaks and Performance Buffs.

We’ve only scratched the surface…

Sanitizing the default Firefox search engine plugins is a good start, but there is much more to do if you’re interested in circumventing the risks to your privacy. For further information see the Tech section of this website.

Resources

Special mention goes to ‘Thorin-Oakenpants’ (aka ‘Pants’) as well as the ‘ghacks’ crew and their GitHub repository where they host an excellent privacy-centric user.js for Firefox and its derivatives, as well as an extensive Wiki full of valuable information.

Revision history

Click to expand...

15-Sep-2017

  • first publish

16-Sep-2017

  • added this change log
  • corrected an error in the pre-sanitized Wikipedia search plugin and re-uploaded sanitized_search_plugs.zip
  • added information as suggested by ‘Pants’ in his comment below, particularly details and resources regarding the followonsearch@mozilla.com.xpi system add-on in a new section titled “Removing the ‘Follow On Search’ system add-on
  • added Hulbee and MetaGer to the search engine list
  • added a “Decentralized” column to the search engine table
  • added resource: 5 Best Search Engines That Respect Your Privacy – BestVPN.com
  • misc. cleanup and edits

17-Sep-2017

  • corrected typo in metager URL
  • added “Requires JS / Cookies” column in search engine table
  • changed links for search engines in table to point to company/about page and added links to point to search page
  • added link to the ‘lite’ version of DDG
  • added a link to the uBO filters to block Startpage/Ixquick tracking images
  • misc. minor edits

18-Sep-2017

  • added “Client Required” column to search engine table
  • corrected some info regarding the search engines in the table
  • minor misc. edits

24-Sep-2017

  • added a link to the Duck Duck Go: Illusion of Privacy article
  • added findx to the search engine list
  • minor edits

27-Sep-2017

  • added Qwant to the search engine table

29-Sep-2017

  • misc. edits and added info, nothing really important

3-Oct-2017

  • very minor edits

23-Oct-2017

  • moved the list of alternative search engines to it own page
  • minor edits

5-Dec-2017

  • minor change to the section ‘Sanitizing the default search engine plugins’ thanks to commenter ‘nohamelin’ – more changes coming shortly thanks to this persons comments

23-Dec-2017

  • updated search plugin import/export instructions as per the very helpful comment left by ‘nohamelin’, the developer of the XML Search Engines Exporter/Importer add-on in which he made available Scratchpad scripts that work with FF v57+
  • corrected an error in the pre-sanitized search engine archive, added Startpage and re-uploaded a new archive
  • misc. minor edits

28-Jan-2018

  • polishing

2-Oct-2018

  • major changes, additions and deletions

3-Oct-2018

  • fixed corrupted download files
  • added info about Add custom search engine add-on
  • added better instructions for installing the search plugin file, search.json.mozlz4
  • minor edits

21-Oct-2018

  • rewrote the section on manually sanitizing search plugins
  • various minor edits

15-Nov-2018

  • updated the search.json.mozlz4 file
  • spelling corrections

27-Nov-2018

  • updated the search.json.mozlz4 file
  • minor edits

11-Dec-2018

  • referred to my Firefox configuration guide for info on removing system add-ons

21-May-2019

  • moved info about Mozilla to it’s own page
  • minor edits, corrections

15 thoughts on “Firefox Search Engine Cautions, Recommendations”

  1. Excellent article 12bytes. Really well done mate :)

    Some items for thought:
    – users should note some engines will require stripping tracking of search *results* (eg utms on google)
    – Firefox has a system add-on called Follow On Search, you should kill that (see ghacks user.js)
    – XML Search Engines Exporter/Importer is not Web Extension (yet?) so for FF57+ users, I guess we can use a portable legacy FF to create the file(s)?

    1. Also remember that in a lot of cases it is better in the first place to use a site specific search engine as well. For example, I have added an iTunes search engine so no-one but iTunes knows I search for Taylor Swift .. #GoTayTay :)

    2. thanks for your input Pants! much appreciated – i updated the article to address this stuff and added a section “Removing the ‘Follow On Search’ system add-on”

      Q: do you know how these system add-ons are loaded – are they loaded dynamically each time FF starts like other add-ons, or are they actually installed/cached some place? i’m wanting to be sure that deleting them is sufficient

      1. System add-ons are listed under about:support>”Firefox Features” – they act just like normal extensions AFAIK (except no disable/uninstall options). Delete the xpi and restart FF and you’re good to go.

        System add-ons are packaged with each Firefox application update (full updates at least). I use portable FF, so I am not sure about installed version behavior re dot releases. If I try to update and I have deleted some system add-on xpi files, the update fails and FF prompts for a full package instead (although the last update from 55.0->55.0.3 didn’t? Can’t remember! Dot releases may vary.). Anyway, I keep an eye on my system add-ons directory, and I only do updates now by downloading the portableapps.com packages (yes they include all the system add-ons too – both 32+64bit app/dirs)

        One of the reasons system add-ons exist, is so that patches/changes can be pushed without an app update. But the update check and update settings can have an effect. See: https://github.com/ghacksuserjs/ghacks-user.js/issues/172 . The ghacks user.js checks for app updates but lets you decide when to apply them – so until this bug is resolved, you won’t get system add-ons re-added or updated without your knowledge.

        You could also try 0505: “extensions.systemAddon.update.url” – if the system doesn’t know where to go, what can it do :) The only reason this is inactive in the js, is because this mechanism was initially designed to PUSH fixes – I think it was spurred on by a critical vulnerability in pdfjs a few years ago (Yes, pdfjs is a system add-on, but seems to be a special case compared to how/where it is stored)

        1. thanks for the clarification

          in my case, with Linux, no system add-ons were displayed in about:support and, actually, there wasn’t even a section called ‘Firefox Features’ – the ‘follow-on search’ add-on wasn’t present either, though others were

      1. I got the message, that it couldn’t be removed as the file/ filecatalog did not exist. english is not my first language, so i’ve translated the message. tech terms may not be correct. I’m no savvy myself, so I’m only familiar with the most common terminal commands. I do attend a local community. they might know about alternatives. yet, I’m the only one pro privacy. off subject: this is a great blog. very user friendly and in depth. thank you @pants for linking at ghacks

  2. (XML Search Engines Exporter/Importer developer here)

    Nice text. I want to add that the list of search plugins included by default in Fx is highly dependent of the build installed: that given list is for the en-US build, I think, and it changes for other locales, according to regional deals done by Mozilla, between other things.

    Now, given that no WebExtensions add-ons interacting with your search engines can be written yet, that leaves us for Fx57+:

    * First, you can get easily the original XML opensearch definition of all the engines included by default navigating to the “resource://search-plugins/” uri. From here, you can inspect them and save them to disk for manual sanitizing.
    * I adapted from the add-on some scripts to import/export engines via Scratchpad; it’s a bit awkward to use, but it should help:
    https://gist.github.com/nohamelin/8e2e1b50dc7d97044992ae981487c6ec
    https://gist.github.com/nohamelin/6af8907ca2dd90a9c870629c396c9521

    Also, be aware that Firefox dropped recently the support for adding engines from the searchplugins/ folder after deleting search.jzon.mozlz4; it will aply since Fx58:
    https://bugzilla.mozilla.org/show_bug.cgi?id=1405670

  3. I realize that this page is somewhat dated, but Linux Mint limits default installed search addons in Firefox to those who have supported their distro’s development, but grudgingly gives a link to a somewhat larger set. I tried to use Scratchpad to install the sanitized search engines downloaded from the included link, but Scratchpad looks for HTML files and doesn’t recognize the sanitized search addons, even if the zip file is unpacked. Maybe I am doing something wrong, but I followed the instructions to the letter, and tried several times. Maybe it doesn’t work in Linux?

    1. I realize that this page is somewhat dated

      actually i updated it today and yesterday

      you don’t have to install the search.json.mozlz4 file – just unpack the .zip and copy the file to your profile directory – if you downloaded the file yesterday, download it again – i changed them

      let me know if you have further problems and, in the mean time, i’ll update the guide with better instructions

  4. Thanks for the useful article;
    how can we detect to which servers/IPs Firefox is sending our information to? so we can block that specific address in windows host file…

    1. if you mean with regard to search engines, you don’t have to – just use alternatives to the default search plugins that ship with Firefox

      if you’re worried about other stuff being sent, i’m not knowledgeable enough to know for certain what Firefox is sending where – you’d have to do your own research – also there are very legitimate reasons for Firefox to be calling home, such as grabbing lists of malicious add-ons, websites, security stuff, etc., so if you block anything, be careful what you block – that said, one of my guides might be of use – another thing you can do is search prefs.js (about:config) for ‘http’

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