** 10/2020 Update **
Using https://tools.epieos.com/google-account.php we can easily enter the Email we want, and to get his GAIA-ID and the links for his Google Maps reviews, Photo Albums, and public calendar (if exist).
Since this hack became more public, Google blocked the option to see the public albums of a user. To bypass this blocking, we should go to – https://get.google.com/albumarchive/GoogleID/albums/profile-photos, and then go back to the user’s public albums. It will only work if the user has a profile picture on his Google account.
Check our video explanation for this hack – https://youtu.be/4WOY_xuGt0Y
** Original Post **
Every user at google (both Gmail users and others) has a unique GAIA ID (Google Accounts and ID Administration ID). This ID is used for identifying the user in Google’s multiple products and can be used to find multiple details about the user.
The easiest way to find the user’s GAIA ID is through the Hangouts web-app. enter https://hangouts.google.com/ and create a New Conversation in the contact area on the left.
Paste the email address you want to explore to the search bar. You’ll get the user card on Hangouts.
Right-click on the user’s card, and select Inspect. It will open you the developer tools of the site on the right.
Look for ‘hovercard-oid’ (make sure the email you searched appears under it after ‘hovercard-email’) and copy the 21-digits ID.
Now that you have the users GAIA ID, you can search it in other Google services, and find out more details about the user.
Try pasting the GAIA ID instead of ‘GoogleID’ in the following links –
1. https://www.google.com/maps/contrib/<GoogleID> (Reviews)
2. https://get.google.com/albumarchive/<GoogleID> (Photo Albums)