Block Site A password protected website access blocker and redirector
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"Block Site" add-on adds a button to your browser's toolbar area. To block a new site (restrict user access) just browse the URL once and press the toolbar button or open the extension's options page and add the hostname (like, or * in the textbox and press the "add" button. This extension accepts master password to allow website access for a short period of time. If the master password is set, you can browse the restricted sites for a pre-defined time period. Also, this extension can be used to redirect a hostname with its arguments to a new destination instead of blocking a hostname (like redirect to a user-defined blocking page). This feature is useful for instance to redirect a search engine into another search engine.



  1. What is "Block Site" extension and how does it work?

    This extension monitors top-level hostname accesses and matches them with a user-defined blocking list. If a hostname is matched, then the access is blocked just before your browser sends the top hostname request to the server. This is useful to prevent access of a hostname that is not supposed to be accessed from your IP address for instance or to prevent popup websites from opening new tabs and hence injecting malicious scripts into your browser.

    The extension also can be used as a URL redirector. To use the extension in the redirecting mode, add a hostname to the blocking list from the options page. Then enter the FULL URL of the destination domain in the redirect box (with schemes like ""). Note that the extension extracts the arguments of the original URL and passes them to the destination URL. This feature is useful to redirect for instance search results from to To do so add "*" as a new hostname and in the destination filed add "". Press the save button for the changes to take place. Now search something in the address bar and you will get the result from

    Note: If it is important that the blocked remote servers do not receive any connection requests, make sure to uncheck "Display title of blocked hostnames" item in the options page. When this item is checked, the extension will send a request to the server and ask for the actual title of the page. This option is useful to distinguish blocked tabs only if there is no restriction to send or receive data from the blocked hostnames.

  2. What is the master password and how can I set it?

    If a master password is set from the options page, you can browse the restricted URL for a pre-defined time period. Also, changing the options (like removing a hostname form the blocking list or changing the time interval of temporary hostname whitelisting) will require the password first. This is mainly useful if you want to prevent other users of the computer to change important settings from the options page.

    Note that by having the master password set, you can browse the blocked websites by entering the master password in the box when a block page is displayed. This will unblock a hostname temporarily for a pre-defined period (1 minute by default).

  3. How can I block all the sub-domains of a single domain (like,, ...)?

    Use wildcard in the place of the subdomain. For instance, to block all the Google subdomains use "*". Here is the list of valid and invalid wildcard matchings:

    PatternWhat it doesExamples of matching URLs
    */foo*matches any host, as long as the path starts with /foo
    **barMatches any URL that uses the https scheme, is on a host (such as,, or, as long as the path starts with /foo and ends with bar
    Bad patternWhy it's bad
    *foo/bar'*' in the host can be followed only by a '.' or '/'
    foo.*.bar/bazIf '*' is in the host, it must be the first character

  4. When a wildcard is used in a matching pattern, the destination redirection feature is disabled. Why?

    This is due to performance drawback of wildcard matching. Wildcard matching is computationally costly and hence this extension does not allow it! You can add multiple rules without wildcard to have the same matching power but without performance drawback.

  5. What's new in this version?

    Please check the Logs section.

  6. Can I change the theme of the blocked pages?

    Yes, as of version 0.1.1, it is possible to choose between dark and light themes. The theme selector is a button that is placed on the top right side of the blocked pages. This option is persistent across browser restarts

  7. Can I block websites for a defined period of time only?

    As of version 0.1.3, there is a new section in the options page to define the time period and days which the blocker is working. Fill this section to block the list for the defined period only. You can also remove a day from the list of days if you want to allow unblocking for that particular day.

  8. Can I use this extension to only allow a few hostnames to be opened and all other hostnames get blocked?

    There is a reverse mode in the options page. If this option is checked, only hostnames that are listed in the list can pass the blockage and all other hostnames will be blocked.

  9. How can I prevent this extension from being removed or disabled from the Firefox browser?

    Create a policies.json file with the following content. This file sits into a directory called distribution within the Firefox installation directory. You can use it to control how users have access to the browser features. For more info visit

      "policies": {
        "Extensions": {
          "Locked":  ["{54e2eb33-18eb-46ad-a4e4-1329c29f6e17}"]
    Mac OS: place the file inside /Applications/

    For Chrome browser see the Set app and extension policies documentation

  10. I have a big list of hostnames to be blocked. Can I import them instead of manually adding new rules?

    Create a text file anywhere on your computer. Let's call it block.txt. The content of this file is a line-separated list of hostnames to be blocked. Basically, each hostname is placed in a new line. If you would like to add comments, use a new line and start the line with "#" character. The extension simply ignores these lines. If you need to enable redirection, add the complete path to the redirected page after the hostname to be blocked. Note that after using the import button, the list will be added to the rules, but still it is not being applied. You need to press the "Save" button for the changes to actually apply. If for any reason, you would prefer to start over, simply close the options page and reopen it. See the sample below:

    # Line-separated list of hostnames to be blocked. Lines start with "#" are ignored
    # hostname to be blocked URL to be redirected to (optional)
    In this example, is being redirected to and is being blocked without any redirection.

  11. Is it possible to pause the blocking for a period instead of using the schedule option? Like when you need to temporary access all the websites for some time.

    Yes, as of version 0.2.3, you can use the right-click context menu over the toolbar button to pause the blocking for a specified period. If your block site is password-protected, you will be asked to unblock the extension first. If pausing is not needed anymore, use the resume item to in the right-click context menu to resume the normal behavior.

  12. Is it possible to have per-domain schedules instead of one schedule that works for all websites?

    As of version 0.2.3, there is a new field on the options page to allow specifying a regular expression rule when defining the scheduling time. If this field is available,the extension only applies the rule to the URLs that match the rule. Otherwise, the global scheduling time is used (if available). To update a schedule with a rule, you need to first load the schedule. To do so enter the rule in the box and wait for the extension to load the information. To delete a schedule with a rule, again enter the rule and wait for the extension to load the rule for you. Then delete the time section and keep the rule so that the extension knows that you want to delete the rule. Now press the save button. Alternatively, you can download all the settings as a JSON object and then modify them with a text editor, then load them back to the extension.

    Here is a minimal example to block on Mondays between 07:00 AM to 08:00 AM. Note that the "" hostname is listed on the blocked list as well as it matches to a regular expression in the scheduling list.

      "blocked": [
      "schedules": {
        "google\\.com": {
          "times": {
            "Mon": [
                "end": "08:00",
                "start": "07:00"

  13. Is it possible to block a website based on a regular expression instead of wildcard matching?

    As of version 0.2.3, you can define a regular expression rule in "Block a new hostname" filed by prepending the rule with R: keyword. This way the extension knows that a regular expression is inserted and hence does not apply the wildcard matching to your rule. Using regular expression you can fine-tune your blocking to match complex domains and keywords.

  14. There is an annoying popup that opens itself once per while. Can I use this extension to automatically close the popup tab?

    Yes, as of version 0.2.3, there is a special redirecting keyword that immediately closes a tab that matches a blocking rule. The keyword is close. So whenever you need to close a tab that is blocked by this extension, use this keyword as the redirection destination.

  15. Is it possible to use this extension on a corporation to block sites on multiple machines?

    As of version 0.3.2, this extension supports managed storage to import settings from the managed preference. An admin user can configure all instances of this extension by setting a managed storage. The PLIST for reading preferences looks like this example. Use your browser managed storage documentation to see how to set up the managed storage.

    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple/DTD PLIST 1.0//EN" "">
    <plist version="1.0">
      <string>single-line valid JSON string containing all the preferences (use the output of the export button + shift key to generate this string)</string>

    By default, this key is set to false, which causes the extension to overwrite all the preferences only once. If the value of this key is set to true, on each restart the extension overwrites all the preference from the provided JSON string. Note that in case the JSON string is updated by the admin (contains a new GUID), all the preferences will be overwritten once even if the "" key is set to false. Also, note that you can set a password while configuring the extension once and this password will prevent all the client machines from altering the preferences later (all clients only access to the HASH of the password so it is safe to set the password on the machine before generating the JSON file).

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What's new in this version

Change Logs:
    Last 10 commits on GitHub
    Hover over a node to see more details

    Need help?

    If you have questions about the extension, or ideas on how to improve it, please post them on the  support site. Don't forget to search through the bug reports first as most likely your question/bug report has already been reported or there is a workaround posted for it.

    Open IssuesIssuesForks

    Editorial Review

    If you feel a website contains such material that needs not to be viewed by your children, younger siblings or any other person in your family, there is an easy way to get that particular website blocked on their system. You can find numerous extensions in the Chrome Web Store’s extensions category to block access to certain websites but not all of them are reliable. Hence, finding the right one can prove to be a daunting task. Block Site extension is one of these extensions that can help you to block access to websites on a system. Wondering whether this extension should be download on your system or not? This review will help you to take the best decision.

    Block Site, a password-protected website blocker extension, aims to make it easier for you to block the access to certain websites. It offers a simple process to block a website. All you have to do is to press the block site icon that will appear on your toolbar once you have downloaded the extension and access to that website will be restricted. Blocking website is not the only feature that Block Site extension boasts of. It can also redirect users to any other website. However, this is a bit complicated process for a beginner as you will have to toggle the extension’s setting and enter the new destination there.

    This extension is perfect to be installed on systems used by kids as they wouldn’t be able to access websites, which contain objectionable materials that you do not want them to view. Whenever they will try to access the blocked website, Restricted Access message will be displayed on their screen.

    A prominent feature that sets Block Site apart from other extensions is “master password”. This extension allows the users to set a master password, which they can use to access the blocked website. The master password also comes with enhanced security features. For example, if a wrong password has been entered multiple times within a minute (you can set manual time here), the access to that website will be blocked. Thus, even if someone is trying to guess the password, they wouldn’t be able to view that particular website as its access will be blocked after wrong attempts.

    What’s Good about this extension?

    Permissions are explained

    tabsTo block a top-level hostname or to redirect a blocked URL when the master password is entered
    storageTo store internal preferences of the extension like the blocked list or redirection map
    <all_urls>To be able to monitor all the top level requests no matter what the hostname is
    webRequestthe main module to observe browser's network activity
    notificationsTo notify the user when an error occurs
    webRequestBlockingComplimentary component to the 'webRequest' API

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