I Studied How Google Signs You Into All Services With One Login. Here's What I Learned

Ever wondered how google connects all its services with one login? How logging into gmail automatically signs you into youTube? these are surprising discoveries I made while exploring

At Hexmos, we have few products—LiveAPI, Feedzap, Feedback, and more to come. Previously, each product required users to sign in separately, which created friction for users to try out other products.

We wanted to solve this by implementing a Single Sign-On (SSO) system. Inspired by Google’s seamless login process, I studied their system, analyzed their login flow, and explored the technical foundations that make it work. Here’s what I learned and how these insights shaped our approach.

Decoding the Magic Behind Google's One-Click Login

Google’s login system is often regarded as the gold standard for seamless authentication. Users can access a wide range of services like Gmail, Drive, and YouTube with a single click, without repeatedly entering credentials. But how does this work behind the scenes?

At its core, Google’s SSO system relies on a combination of Identity Providers (IdPs), Service Providers (SPs), cookies, tokens, and robust protocols to manage authentication across domains and services. By examining their approach, we can understand the building blocks of an effective SSO implementation.

Google's Identity Arsenal: Identity Providers and Service Providers

In the SSO ecosystem, Google exemplifies the interaction between Identity Providers (IdPs) and Service Providers (SPs) to enable seamless user experiences:

• Identity Providers (IdPs): IdPs authenticate users and issue tokens or credentials verifying their identity. Google’s IdP, for example, allows users to log in once and access services like Gmail, YouTube, or Google Drive.

• Service Providers (SPs):  SPs consume the authentication the IdP provides. When a user logs in to accounts.google.com (the IdP), other services like Google Docs or Calendar (SPs) trust the credentials issued by the IdP and allow access without a second login.

This relationship ensures secure, unified access management while eliminating redundant authentication, streamlining both user experience and security processes.

Analising Google's Login Flow By Seeing Network Requests

1. First Time Signing in I am Trying to access Google Meet

This page Will Open in same tab
URL:

https://accounts.google.com/...&checkConnection=youtube%3A613&checkedDomains=youtube&...&continue=https%3A%2F%2Fmeet.google.com%3Fhs%3D193&...

I observed the following network requests:

• checkConnection and checkedDomains query parameters:
  &checkConnection=youtube%3A613&checkedDomains=youtube
  
  Indicates that the login process might connect to YouTube as well.

• Post-login redirect:
  &continue=https%3A%2F%2Fmeet.google.com%3Fhs%3D193
  
  After signing in, the user will be redirected to Google Meet at https://meet.google.com?hs=193.

After Signing in

Description: This image shows the page displayed after redirection from the login page.

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