Employees often need to log in to multiple apps to do their daily work. In the past, simple username and password combos were adequate for accessing the small number of apps that an enterprise might use. These days, enterprise app sprawl has increased the average number of SaaS apps used by organizations to 130. This multitude of apps has made single sign-on (SSO) a necessity for any enterprise. SSO improves the employee experience and increases productivity. 

Today’s workforce relies on dozens, sometimes hundreds, of SaaS applications to perform daily tasks. In the past, managing app access with simple usernames and passwords worked when companies used only a few core systems.

SSO simplifies the login process for employees and helps IT teams manage security and access control at scale. In 2025, with hybrid work and SaaS sprawl dominating business environments, SSO plays a critical role in improving productivity, reducing security risks, and enforcing centralized identity management.

What is SSO?

Single Sign-On (SSO) is a centralized authentication method that allows users to log in once and access multiple connected applications without re-authenticating for each one.

It has revolutionized credential management — it’s a seamless way for employees to authenticate themselves across multiple apps and websites. SSO works remotely and within the confines of a corporate network. It simplifies the user experience, as employees and other users don't need to remember multiple usernames and passwords. 

SSO tokens have a controlled lifespan. Administrators can configure token expiration and session policies to align with organizational security needs. Once expired, users must authenticate again, maintaining a balance between user convenience and security enforcement.

The lexicon of SSO

Understanding SSO starts with knowing the terminology used in identity and access management:

Understanding SSO starts with knowing the terminology used in identity and access management:

• Federated identity: SSO is part of a federated identity system. SSO is responsible for the authentication aspect of federated identity.

• SSO token: The SSO process generates an authentication token that allows access to federated apps and websites. SSO tokens are essentially digital authentication credentials used to authenticate access to multiple applications and websites. 

• Authentication service or SSO service: This is a service that handles the login credentials and issues SSO tokens.

These components work together to streamline access across a broad ecosystem of applications, both on-premises and in the cloud.

Protocols supporting SSO

SSO functions through standardized protocols designed to securely exchange identity information:

SAML (Security Assertion Markup Language) tokens

SAML is a well-established open standard authentication protocol. One of the main reasons for developing SAML was to offer provision for cross-domain SSO.

OIDC (OpenID Connect)

OIDC is an identity layer built on the OAuth 2.0 framework. OIDC uses JSON Web Tokens (JWTs) to exchange data between an identity provider (IdP) and a service provider (SP). OIDC can be implemented to handle SSO.

How does SSO work?

SSO can be implemented in several ways, depending on your security and user needs. However, the general flow of an SSO exchange begins when a user attempts to log in to a supported app or service website. 

During login, a redirection to the authentication server (SSO service) occurs, and what occurs next depends on whether:

• The user is still logged in to an SSO session: The service checks to see whether the user is already logged in to a SSO session. If they are, then the service issues an access token to access the app (the app must have an account with the authentication server).

• The user has yet to log in: If the user is not logged in, they will be asked to present their login credentials, and an access token will be issued.

Once authenticated, the user gains seamless access to other connected applications within the SSO environment, improving workflow efficiency and minimizing login interruptions.

Classic SSO flow

Most SSO services check user credentials against a separate identity management service. The session token is typically stored as a cookie or in the user's browser.

What about single logout (SLO)?

When you’re implementing SSO, it’s important to also configure SLO. This way, when a user logs out of one app, the SSO token is destroyed, improving the security of the overall ecosystem.

Benefits of SSO

Some of the most important benefits of using SSO are:

Better user experiences 

Faster login and fewer passwords to remember lead to better employee and non-employee experiences.

Improved productivity

A better employee experience and less time spent logging in to apps and websites improve productivity.

Less credential sprawl and password fatigue

Remembering multiple passwords for myriad apps causes password fatigue. SSO removes the need to remember dozens of passwords. SSO also reduces the likelihood of poor password hygiene, such as writing passwords down on paper. On the administrator side, SSO helps to alleviate password sprawl and reduces password management overhead.

Reduced IT support costs

SSO reduces the time support staff has to spend on helping users recover or reset passwords. Since many organizations use dozens, if not hundreds, of apps, password recovery can become onerous. 

What is the SSO Tax?

Recently, the idea of an "SSO tax" has been discussed. This is the practice of SaaS vendors charging more for access to their SSO capabilities. The argument goes that any company with five or more employees should have the benefits of SSO. However, vendors offering identity management tools often provide SSO only in a higher-tier, much more expensive version, effectively levying a burdensome “tax” on smaller organizations that also need SSO.

In many cases, vendors lock SSO behind enterprise-tier plans, making it financially challenging for small to mid-sized businesses to secure their environments effectively. With security becoming a baseline expectation rather than a premium feature, this practice remains controversial. In 2025, industry advocacy continues to push for fairer access to essential identity and security capabilities for organizations of all sizes.

SSO and security

The security of an SSO service is dependent on its implementation. However, several aspects of SSO help improve enterprise security:

• App or website legitimacy: When a user wants to access a service or an app, a digitally signed authentication request is generated. The authentication server then verifies that the request is legitimate. Only when the app has been authenticated does the authentication service check to find out whether the user is logged in (or needs to go through the login process), and then an access token is issued.

• MFA (multi-factor authentication): SSO supports MFA, but MFA enforcement can be based on risk level. For example, apps that contain sensitive information may require an MFA during login, whereas other, less sensitive operations will use SSO auto-login.

• Risk-based SSO: The re-entering of credentials can be enforced after a specific time period. SSO centralizes this control and enforces the policy across multiple federated apps.

In today's world, combining SSO with zero-trust security models strengthens enterprise defenses against credential theft, phishing, and unauthorized access.

Do social logins support SSO?

Many social logins can act as a form of SSO. Social logins are provided by platforms such as Facebook and LinkedIn, as well as platforms like Apple. Services and websites that support the various social login providers allow users to log in to cross-domain accounts that support social SSO. Social logins like LinkedIn’s can reduce the friction between customer and employee onboarding and access to resources.

Who provides SSO?

Many identity providers (IdPs) offer robust SSO capabilities, each often supporting SAML, OIDC, or both. Notable providers include:

• Okta enterprise SSO solution.

• OneLogin: covers customers and the workforce and has good SecOps features.

• Ping Identity: a full range of identity capabilities, including SSO.

• Microsoft Entra ID (previously Active Directory): Microsoft's ubiquitous identity service offers SSO for Windows and SaaS environments.

• Google Cloud Identity 

These providers enable organizations to manage access centrally while integrating with SaaS ecosystems, on-prem apps, and hybrid infrastructures.

SSO in a Zero Trust Environment

In a zero trust architecture, SSO works hand in hand with continuous authentication, device trust checks, and least privilege access.

SSO reduces friction without weakening security by acting as a gateway to enforce contextual access policies. Modern implementations integrate with adaptive risk engines that evaluate login behavior, device health, and geographic factors before granting access.

The Future of SSO: AI, Automation, and Threat Response

SSO is evolving beyond access management into a strategic component of enterprise security operations. In 2025, SSO platforms increasingly offer:

• AI-powered anomaly detection for unusual login patterns

• Automated incident response when compromised credentials are suspected

• Real-time integration with SIEM and SOAR platforms for threat hunting and security operations

As identity remains a top attack vector, AI-enhanced SSO is becoming a key player in proactive cybersecurity strategies.

Conclusion: Why SSO is a Must-Have in 2025

SSO improves security, enhances user experience, and simplifies IT management in increasingly complex digital environments.

In 2025, as hybrid work, SaaS expansion, and regulatory pressures grow, SSO stands out as a critical tool for organizations looking to scale securely and efficiently. When combined with identity governance, MFA, and automation, SSO forms a cornerstone of modern identity and access management strategies.

Read more about the limitations of SSO.