LDAP vs. SSO explained: key differences and use cases

At first glance, LDAP and SSO might seem like competing authentication tools, but the truth is more nuanced. LDAP is an open protocol for querying and maintaining data in directories, while SSO is an authentication method that allows users to log in once and access multiple apps.

And here’s the link: SSO relies on centralized directories to verify users, and sometimes, these directories are LDAP-based, though not always.

In this article, we'll walk you through:

• What LDAP and SSO are
• Pros and cons of each
• When to use which or both

Let’s start by quickly comparing LDAP vs SSO.

LDAP vs. SSO: TL;DR

LDAP is used to centralize user identities in a structured directory and manage access to all resources within an enterprise network.

SSO simplifies user access across multiple apps and services, allowing users to log in once and gain access to all the apps they have permission to.

So, which one should you choose?

• Use LDAP if your app supports on-premises deployments and needs to authenticate users against local directories.
• Use SSO if you’re building a cloud-based app and want centralized authentication to simplify user access across apps.
• Use SSO with LDAP if you want to authenticate users who are stored in an LDAP directory.

For all the details, check out the full explanations below.

What is LDAP?

LDAP, or Lightweight Directory Access Protocol, is a protocol that governs how information is accessed and managed over a network. It is specifically designed for directory services, which act as centralized repositories for user and device data.

The primary job of directory services using LDAP is to facilitate efficient searches and updates in these directories, whether for managing users, configuring services, or accessing resources.

LDAP also supports authentication when integrated with directories like Active Directory.

Here’s how it works:

• When a user tries to access a system or application, the client (e.g., an app) sends an authentication request to the LDAP server.
• The server searches its directory to verify the user’s identity and determine their permissions or access levels.
• Based on this information, the user is authenticated through their credentials and authorized to access the appropriate resources.

While LDAP isn’t an SSO solution, LDAP-based directories can act as a central hub for user credentials. SSO providers can then use these directories to authenticate users.

Pros of LDAP

LDAP has the following benefits:

• Centralized management of identities: LDAP-used directories consolidate user data into a single directory, which makes it easier for admins to manage user accounts and permissions across the network.
• Scalability: It is highly scalable and capable of handling thousands of entries and modifications without significant performance degradation. Plus, you can set up LDAP clusters for even larger deployments.
• Fast reads: LDAP is optimized for fast search and retrieval, allowing admins to locate user or resource information quickly—even in extensive directories.
• Interoperability: Being vendor-neutral, LDAP is supported by various applications, operating systems, and network devices, making it compatible with diverse IT environments.

Cons of LDAP

Below are some of the downsides of LDAP:

• Inefficient write operations: While LDAP excels at read operations, frequent write actions — such as bulk updates or adding numerous entries — can slow it down, making it less ideal for dynamic systems with high write demands.
• Complex setup and maintenance: Setting up an LDAP server and directory requires skilled IT staff to configure and maintain, especially in larger environments with extensive security and customization needs.
  
  For example, modifying the LDAP schema to accommodate custom requirements can be complicated and, if not done carefully, may lead to issues with data integrity.

What is SSO?

Single Sign-On (SSO) is an authentication method that allows users to log in once and gain access to multiple applications without needing to re-authenticate.

Here’s how it works: When a user logs in, the identity provider authenticates them and issues a token containing details about their identity. The app then uses this token to grant access without further prompts.

This process relies on standard protocols like:

• SAML: An XML-based protocol popular in enterprises, SAML facilitates Single Sign-On by exchanging authentication data between an identity provider (IdP) and a service provider (SP). After authenticating with the IdP, users receive a SAML assertion that the SP uses to log them in.
• OpenID Connect: Built on OAuth 2.0, OIDC is more lightweight and modern, making it a favorite for mobile apps and APIs. Unlike SAML, OIDC uses JSON Web Tokens (JWTs) to pass user data, which makes it more flexible and easier to implement.

Pros of SSO

SSO offers significant benefits, including:

• User convenience: Users log in once and can access all their apps without being asked to log in again — that's a big win for productivity
• Increased security: Everything is managed centrally, making it easier to enforce MFA or track access for compliance.
• Reduced IT costs: It saves time and money — fewer support calls for password resets and less work for developers because the customer’s IdP handles authentication.

Cons of SSO

Some of the disadvantages of SSO include:

• Increased vulnerability: SSO creates a single point of failure — if someone hacks your customer’s directory, they can access everything, including your app. Also, since SSO relies on one set of credentials for many apps, the risk is much higher if those credentials are stolen.
• Implementation complexity: Implementing SSO can get tricky because different identity providers use other protocols, like SAML or OpenID Connect, and each has quirks. Your team might spend much time figuring out and supporting all those variations.

Frequently Asked Questions

How to use SSO with LDAP?

LDAP is not an SSO protocol but a communication protocol for accessing directories. However, an SSO provider can integrate with LDAP to allow someone with an on-premises LDAP directory to use that directory and credentials to authenticate users.

What is the difference between LDAP and Active Directory?

LDAP is a protocol for querying and modifying directory services running over a network. It is platform-independent and can be used with various directory service implementations.

Active Directory (AD), from Microsoft, is one of the directory services that can use LDAP.

For more on this see LDAP vs Active Directory: Differences + What you need to know.

Can SSO work without LDAP?

Yes, SSO can work without LDAP. SSO is a high-level authentication scheme that can leverage various user directories (not just LDAP-based directories) and authentication protocols, including OAuth, OpenID Connect, and SAML.

What is the difference between LDAP and SCIM?

LDAP is a protocol for querying and maintaining a directory over a network. It does not define how data is synchronized between systems. SCIM is designed to synchronize user data between an IdP and an SP using REST APIs.

For more on this see SCIM vs. LDAP: Key differences + Which to use.

Next steps with WorkOS

When it comes to SSO authentication, SAML and OIDC are the go-to protocols, but implementing them doesn’t have to be a hassle. Use WorkOS and connect to multiple identity providers like Okta, OneLogin, and Microsoft Entra in minutes.

• Get started fast: With SDKs in every popular language, easy-to-follow documentation, and Slack-based support, you can implement SSO in minutes rather than weeks.
• Support every protocol: With OAuth 2.0 integrations to popular providers like Google and Microsoft, compatibility with every major IdP, and full support for custom SAML/OIDC connections, WorkOS can support any enterprise customer out of the box.
• Avoid the back-and-forth: WorkOS’s Admin Portal takes the pain out of onboarding your customers’ IT teams and configuring your app to work with their identity provider.
• Pricing that makes sense: Unlike competitors who price by monthly active users, WorkOS charges a flat rate for each company you onboard — whether they bring 10 or 10,000 SSO users to your app.

Explore Unified SSO by WorkOS.