An authentication method that allows users to log in once and access all connected applications without re-entering credentials. SSO simplifies the login experience while centralizing authentication control for IT teams.
What SSO Does
Single Sign-On lets you log in once to a central identity provider, and that login carries you across every connected application (Slack, Google Workspace, GitHub, Salesforce, your HRIS, your finance tool) without re-authenticating for each one. One event covers everything.
The appeal for users is obvious: fewer passwords, less friction, one login to remember. But SSO is not primarily a UX feature. It's a security architecture decision. When authentication flows through one provider, you get one place to enforce policies, one place to revoke access, and one audit trail covering every login event across your entire application stack.
The alternative, individual credentials for every application, creates security debt that compounds. Users reuse passwords. They use weak ones. They do not change them when they leave a company. SSO removes most of that risk because the identity provider handles authentication; applications just trust that provider.
How SSO Works
SSO uses protocols, most commonly SAML (Security Assertion Markup Language) or OAuth/OIDC, to pass authentication tokens between the identity provider and each application. When a user tries to access an app, the app asks the identity provider: has this person authenticated? If yes, and if they're authorized, access is granted. The user never enters a password directly into the application.
Common identity providers include Okta, Azure Active Directory, Google Workspace, and OneLogin. Applications that support SSO accept the token from these providers without maintaining a separate password database.
SSO and Offboarding
SSO makes offboarding immediate and complete. When an employee leaves, disabling their identity provider account cuts access to every connected application simultaneously. No working through a list of 40 applications hoping you caught them all. For organizations managing distributed teams with dozens of SaaS tools, this is one of SSO's most important operational benefits.
SSO and Security
SSO concentrates authentication into one point, which means that point needs strong protection. MFA on the identity provider is non-negotiable. If an attacker gains access to the IdP, they have access to every connected application. The upside is that one strong authentication event with MFA is far more secure than dozens of weak individual passwords.
When SSO Becomes Essential
For small teams, SSO is convenient. For growing organizations, it becomes necessary infrastructure. Once a company exceeds 50 employees and a dozen applications, managing individual credentials becomes unmanageable: onboarding takes longer, offboarding leaves gaps, and security posture degrades as password hygiene slips. SSO is the structural fix, not the band-aid.