Use Google Chrome Incognito Mode as default mode on macOS

When working on Web Development projects, I often find myself needing to test the website in Incognito Mode.

By default I use Firefox and Google Chrome as browsers for testing, when it comes to Firefox setting up a default “Incognito Mode” is pretty straightforward, I just disable History and Cookies in the settings and I’m good to go.

However, when it comes to Google Chrome, there is no such setting, so I rely on openning Google Chrome and then switch it to Incognito Mode manually, which is a bit annoying. I wanted to have Google Chrome open in Incognito Mode by default.

About defaults command

If you are a macOS user, you might have seen plist files, these files are used to store user preferences for applications. You can use the defaults command to read, write, and delete these preferences.

Open your terminal and run defaults command to see the help message.

Command line interface to a user's defaults.
Syntax:

'defaults' [-currentHost | -host <hostname>] followed by one of the following:

  read                                 shows all defaults
  read <domain>                        shows defaults for given domain
  read <domain> <key>                  shows defaults for given domain, key

  read-type <domain> <key>             shows the type for the given domain, key

  write <domain> <domain_rep>          writes domain (overwrites existing)
  write <domain> <key> <value>         writes key for domain

  rename <domain> <old_key> <new_key>  renames old_key to new_key

  delete <domain>                      deletes domain
  delete <domain> <key>                deletes key in domain
  delete-all <domain>                  deletes the domain from all containers
  delete-all <domain> Key>             deletes key in domain from all containers

  import <domain> <path to plist>      writes the plist at path to domain
  import <domain> -                    writes a plist from stdin to domain
  export <domain> <path to plist>      saves domain as a binary plist to path
  export <domain> -                    writes domain as an xml plist to stdout
  domains                              lists all domains
  find <word>                          lists all entries containing word
  help                                 print this help

<domain> is ( <domain_name> | -app <application_name> | -globalDomain )
         or a path to a file omitting the '.plist' extension

<value> is one of:
  <value_rep>
  -string <string_value>
  -data <hex_digits>
  -int[eger] <integer_value>
  -float  <floating-point_value>
  -bool[ean] (true | false | yes | no)
  -date <date_rep>
  -array <value1> <value2> ...
  -array-add <value1> <value2> ...
  -dict <key1> <value1> <key2> <value2> ...
  -dict-add <key1> <value1> ...

Each application has its own plist file, for Google Chrome it’s located at ~/Library/Preferences/com.google.Chrome.plist.

Setting Google Chrome to open in Incognito Mode by default

Knowing about the defaults command and the location of the plist file, we can now set Google Chrome to open in Incognito Mode by default.

You can check for the current defaults on Google Chrome easily by running the following command:

defaults read com.google.chrome

Between many options (also known as keys) available, we are interested in the IncognitoModeAvailability key, which is set to 0 by default.

The IncognitoModeAvailability key can have the following values:

Value	Description
0	Incognito mode available.
1	Incognito mode disabled.
2	Incognito mode forced.

As I want to always use Incognito Mode, I will set the IncognitoModeAvailability key to 2, to do this run the following command:

defaults write com.google.chrome IncognitoModeAvailability -integer 2

Now, when you open Google Chrome, it will open in Incognito Mode by default. In order for these changes to take effect, you will need to restart your system!

I know, its actually weird in macOS to restart the system for application settings to take effect but Preferences are loaded at the time of login, so you need to restart your system to apply the changes.

Setting up an alias to have Google Chrome in incognito mode

If you don’t want to restart your system, you can set up an alias to open Google Chrome in Incognito Mode.

This approach will allow you to open Google Chrome in Incognito Mode from a bash alias without having to update preferences settings.

Open your .bashrc or .zshrc file and add the following alias:

alias chrome="open -a /Applications/Google\ Chrome.app --args --incognito"

Then run the following command to apply the changes:

source ~/.bashrc

or, if you are using ZSH:

source ~/.zshrc

Now you can open Google Chrome in Incognito Mode by running the following command:

chrome