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Single Sign-On with SAML 2.0 for Projects

Looking for guides on how to use Single Sign-On with the Supabase dashboard? Head on over to Enable SSO for Your Organization.

Supabase Auth supports enterprise-level Single Sign-On (SSO) for any identity providers compatible with the SAML 2.0 protocol. This is a non-exclusive list of supported identity providers:

If you're having issues with identity provider software not on this list, open a support ticket.

Prerequisites#

This guide requires the use of the Supabase CLI. Make sure you're using version v1.46.4 or higher. You can use supabase -v to see the currently installed version. You can use the supabase sso subcommands to manage your project's configuration.

SAML 2.0 support is disabled by default on Supabase projects. You can configure this on the Auth Providers page on your project.

Note that SAML 2.0 support is offered on plans Pro and above. Check the Pricing page for more information.

Terminology#

The number of SAML and SSO acronyms can often be overwhelming. Here's a glossary which you can refer back to at any time:

Important SAML 2.0 information#

Below is information about your project's SAML 2.0 configuration which you can share with the company or organization that you're trying to on-board.

Name

Value

EntityID

https://<project>.supabase.co/auth/v1/sso/saml/metadata

Metadata URL

https://<project>.supabase.co/auth/v1/sso/saml/metadata

Metadata URL
(download)

https://<project>.supabase.co/auth/v1/sso/saml/metadata?download=true

ACS URL

https://<project>.supabase.co/auth/v1/sso/saml/acs

SLO URL

https://<project>.supabase.co/auth/v1/sso/slo

NameID

Required emailAddress or persistent

Note that SLO (Single Logout) is not supported at this time with Supabase Auth as it is a rarely supported feature by identity providers. However, the URL is registered and advertised for when this does become available. SLO is a best-effort service, so we recommend considering Session Timebox or Session Inactivity Timeout instead to force your end-users to authenticate regularly.

Append ?download=true to the Metadata URL to download the Metadata XML file. This is useful in cases where the identity provider requires a file.

Alternatively, you can use the supabase sso info --project-ref <your-project> command to get setup information for your project.

User accounts and identities#

User accounts and identities created via SSO differ from regular (email, phone, password, social login...) accounts in these ways:

Row Level Security#

You can use information about the SSO identity provider in Row Level Security policies.

Here are some commonly used statements to extract SSO related information from the user's JWT:

If you use Multi-Factor Authentication with SSO, the amr array may have a different method at index 0!

A common use case with SSO is to use the UUID of the identity provider as the identifier for the organization the user belongs to -- frequently known as a tenant. By associating the identity provider's UUID with your tenants, you can use restrictive RLS policies to scope down actions and data that a user is able to access.

For example, let's say you have a table like:

1create table organization_settings (2  -- the organization's unique ID3  id uuid not null primary key,4  -- the organization's SSO identity provider5  sso_provider_id uuid unique,6  -- name of the organization7  name text,8  -- billing plan (paid, Free, Enterprise)9  billing_plan text10);

You can use the information present in the user's JWT to scope down which rows from this table the user can see, without doing any additional user management:

1CREATE POLICY "View organization settings."2  ON organization_settings3  AS RESTRICTIVE4  USING (5    sso_provider_id = (select auth.jwt()#>>'{amr,0,provider}')6  );

Managing SAML 2.0 connections#

Once you've enabled SAML 2.0 support on your project via the Auth Providers page in the dashboard, you can use the Supabase CLI to add, update, remove and view information about identity providers.

Add a connection#

To establish a connection to a SAML 2.0 Identity Provider (IdP) you will need:

You should obtain the SAML 2.0 Metadata XML file or URL from the organization whose IdP you wish to connect. Most SAML 2.0 Identity Providers support the Metadata URL standard, and we recommend using a URL if this is available.

Commonly used SAML 2.0 Identity Providers that support Metadata URLs:

Commonly used SAML 2.0 Identity Providers that only support Metadata XML files:

Once you've obtained the SAML 2.0 Metadata XML file or URL you can establish a connection with your project's Supabase Auth server by running:

1supabase sso add --type saml --project-ref <your-project> \2  --metadata-url 'https://company.com/idp/saml/metadata' \3  --domains company.com

If you wish to use a Metadata XML file instead, you can use:

1supabase sso add --type saml --project-ref <your-project> \2  --metadata-file /path/to/saml/metadata.xml \3  --domains company.com

This command will register a new identity provider with your project's Auth server. When successful, you will see the details of the provider such as it's SAML information and registered domains.

Note that only persons with write access to the project can register, update or remove identity providers.

Once you've added an identity provider, users who have access to it can sign in to your application. With SAML 2.0 there are two ways that users can sign in to your project:

To initiate a sign-in request from your application's user interface (i.e. the SP Initiated Flow), you can use:

1import { createClient } from '@supabase/supabase-js'23const supabase = createClient('https://your-project-id.supabase.co', 'sb_publishable_...')45// ---cut---6supabase.auth.signInWithSSO({7  domain: 'company.com',8})

Calling signInWithSSO starts the sign-in process using the identity provider registered for the company.com domain name. It is not required that identity providers be assigned one or multiple domain names, in which case you can use the provider's unique ID instead.

Understanding attribute mappings#

When a user signs in using the SAML 2.0 Single Sign-On protocol, an XML document called the SAML Assertion is exchanged between the identity provider and Supabase Auth.

This assertion contains information about the user's identity and other authentication information, such as:

With exception of the unique user ID, SAML does not require any other attributes in the assertion. Identity providers can be configured so that only select user information is shared with your project.

Your project can be configured to recognize these attributes and map them into your project's database using a JSON structure. This process is called attribute mapping, and varies according to the configuration of the identity provider.

For example, the following JSON structure configures attribute mapping for the email and first_name user identity properties.

1{2  "keys": {3    "email": {4      "name": "mail"5    },6    "first_name": {7      "name": "givenName"8    }9  }10}

When creating or updating an identity provider with the Supabase CLI you can include this JSON as a file with the --attribute-mapping-file /path/to/attribute/mapping.json flag.

For example, to change the attribute mappings to an existing provider you can use:

1supabase sso update <provider-uuid> --project-ref <your-project> \2  --attribute-mapping-file /path/to/attribute/mapping.json

Given a SAML 2.0 assertion that includes these attributes:

1<saml:AttributeStatement>2  <!-- will be mapped to the email key -->3  <saml:Attribute4    Name="mail"5    NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic"6    >7    <saml:AttributeValue xsi:type="xs:string">8      valid.email@supabase.io9    </saml:AttributeValue>10  </saml:Attribute>1112  <!-- will be mapped to the first_name key -->13  <saml:Attribute14    Name="givenName"15    NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic"16    >17    <saml:AttributeValue xsi:type="xs:string">18      Jane Doe19    </saml:AttributeValue>20  </saml:Attribute>21</saml:AttributeStatement>

Will result in the following claims in the user's identity in the database and JWT:

1{2  "email": "valid.email@supabase.io",3  "custom_claims": {4    "first_name": "Jane Doe"5  }6}

Supabase Auth does not require specifying attribute mappings if you only need access to the user's email. It will attempt to find an email attribute specified in the assertion. All other properties will not be automatically included, and it is those you need to map.

At this time it is not possible to have users without an email address, so SAML assertions without one will be rejected.

Most SAML 2.0 identity providers use Lightweight Directory Access Protocol (LDAP) attribute names. However, due to their variability and complexity operators of identity providers are able to customize both the Name and attribute value that is sent to Supabase Auth in an assertion. Refer to the identity provider's documentation and contact the operator for details on what attributes are mapped for your project.

Accessing the stored attributes

The stored attributes, once mapped, show up in the access token (a JWT) of the user. If you need to look these values up in the database, you can find them in the auth.identities table under the identity_data JSON column. Identities created for SSO providers have sso:<uuid-of-provider> in the provider column, while id contains the unique NameID of the user account.

Furthermore, you can find the same identity data under raw_user_meta_data inside auth.users.

Advanced attribute mapping

If the SAML assertion contains multiple values for a key, such as the groups that the user has access to, only the first one will be picked up. To change this behavior, mark the key as an array. For example this attribute mapping:

1{2  "keys": {3    "groups": {4      "name": "groups",5      "array": true6    }7  }8}

Will result in the following claims:

1{2  "groups": ["group-a", "group-b", "group-c"]3}

You can also specify a default value for a key that may be missing in the SAML assertion.

1{2  "keys": {3    "custom_claim": {4      "name": "custom_claim",5      "default": 1236    }7  }8}

Some SAML Assertions may expose the same attribute under different names for different users. In this case instead of specifying a single name to look up the value, you can specify multiple names. These will be looked at in-order until a value is found:

1{2  "keys": {3    "custom_claim": {4      "names": ["first-look-for-this-attribute", "then-this-one"]5    }6  }7}

Remove a connection#

Once a connection to an identity provider is established, you can remove it by running:

1supabase sso remove <provider-id> --project-ref <your-project>

If successful, the details of the removed identity provider will be shown. All user accounts from that identity provider will be immediately logged out. User information will remain in the system, but it will no longer be possible for any of those accounts to be accessed in the future, even if you add the connection again.

A list of all registered identity providers can be displayed by running:

1supabase sso list --project-ref <your-project>

Update a connection#

You may wish to update settings about a connection to a SAML 2.0 identity provider.

Commonly this is necessary when:

You can use this command to update the configuration of an identity provider:

1supabase sso update <provider-id> --project-ref <your-project>

Use --help to see all available flags.

It is not possible to change the unique SAML identifier of the identity provider, known as EntityID. Everything else can be updated. If the SAML EntityID of your identity provider has changed, it is regarded as a new identity provider and you will have to register it like a new connection.

Retrieving information about a connection#

You can always obtain a list of all registered providers using:

1supabase sso list --project-ref <your-project>

This list will only include basic information about each provider. To see all of the information about a provider you can use:

1supabase sso show <provider-id> --project-ref <your-project>

You can use the -o json flag to output the information as JSON, should you need to. Other formats may be supported, use --help to see all available options.

Pricing#

$0.015 per SSO MAU. You are only charged for usage exceeding your subscription plan's quota.

For a detailed breakdown of how charges are calculated, refer to Manage Monthly Active SSO Users usage.

Frequently asked questions#

Publishing your application to an identity provider's marketplace#

Many cloud-based identity providers offer a marketplace where you can register your application for easy on-boarding with customers. When you use Supabase Auth's SAML 2.0 support you can register your project in any one of these marketplaces.

Refer to the relevant documentation for each cloud-based identity provider on how you can do this. Some common marketplaces are:

Why do some users get: SAML assertion does not contain email address?#

Identity providers do not have to send back and email address for the user, though they often do. Supabase Auth requires that an email address is present.

The following list of commonly used SAML attribute names is inspected, in order of appearance, to discover the email address in the assertion:

Finally if there is no such attribute, it will use the SAML NameID value but only if the format is advertised as urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress.

Should you run into this problem, it is most likely a misconfiguration issue on the identity provider side. Instruct your contact at the company to map the user's email address to one of the above listed attribute names, typically email.

Accessing the private key used for SAML in your project#

At this time it is not possible to extract the RSA private key used by your project's Supabase Auth server. This is done to keep the private key as secure as possible, given that SAML does not offer an easy way to rotate keys without disrupting service. (Use a SAML 2.0 Metadata URL whenever possible for this reason!)

If you really need access to the key, open a support ticket and we'll try to support you as best as possible.

Is multi-tenant SSO with SAML supported?#

Yes, Supabase supports multi-tenant Single Sign-On (SSO) using SAML 2.0. While the dashboard displays only one SAML field, you can set up multiple SAML connections using the Supabase CLI. Each connection is assigned a unique sso_provider_id, which is included in the user's JWT and can be used in Row Level Security (RLS) policies. You can configure custom attribute mappings for each connection to include tenant-specific information, such as roles. This setup allows you to implement multi-tenant SSO for multiple clients or organizations within a single application. For example, if you have an app with multiple clients using different Azure Active Directories, you can create separate SAML connections for each and use the sso_provider_id to manage access and apply appropriate security policies.

Is multi-subdomain SSO with SAML supported?#

Yes, also referred to as cross-origin authentication within the same site. To redirect to a URL other than the Site URL, following the SAML response from the IdP, the redirectTo option can be added to signInWithSSO.

1import { createClient } from '@supabase/supabase-js'23const supabase = createClient('https://your-project-id.supabase.co', 'sb_publishable_...')45// ---cut---6const { data, error } = await supabase.auth.signInWithSSO({7  domain: 'company.com',8  options: {9    redirectTo: `https://app.company.com/callback`,10  },11})

When redirecting to a URL other than the Site URL, a /callback endpoint is necessary to process the auth code from the IdP and exchange it for a session. This assumes the Supabase SSR client has already been configured.

1import { error, redirect } from '@sveltejs/kit'23import type { RequestHandler } from './$types'45export const GET: RequestHandler = async ({ url, locals }) => {6  const code = url.searchParams.get('code')78  if (!code) {9    error(400, 'No authorization code provided')10  }1112  const { error: tokenExchangeError } = await locals.supabase.auth.exchangeCodeForSession(code)1314  if (tokenExchangeError) {15    error(400, 'Failed to exchange authorization code for session')16  }1718  redirect(303, '/')19}

Why doesn't IdP-initiated SAML flow work with PKCE, and what's the alternative?#

Traditional IdP-initiated SAML flows aren't compatible with PKCE (Proof Key for Code Exchange) because PKCE requires a code_challenge and code_verifier that are generated when your application initiates the authentication flow. In IdP-initiated flows, Supabase receives an unsolicited response without this information, causing the code exchange step to fail.

To achieve the same user experience while maintaining PKCE security, you can implement a "bookmark app" approach:

Create an endpoint in your application (for example, https://your-app.com/auth/saml-init) that initiates the SAML flow using signInWithSSO. Then create a bookmark or linked application in your IdP that points to this endpoint. When users access the bookmark app, it triggers a secure SP-initiated flow.

This approach supports custom SAML assertions and lets you embed the link anywhere in your application.