WorkOS vs Auth0 for MCP: OAuth for Remote MCP Servers (2026)

Pick WorkOS if you want a large free tier for user sign-ins and an easy way to keep your existing login while adding MCP OAuth. Pick Auth0 if your MCP server must call other APIs as the signed-in user, because its Token Vault and On-Behalf-Of token exchange are built for that. Both act as the OAuth authorization server for a remote MCP server and both support Client ID Metadata Documents.

Checked against: WorkOS AuthKit MCP docs and Auth0 Auth for MCP docs on 28 October 2026. eSEOspace did not test either product.

The MCP authorization spec splits sign-in into two roles. Your MCP server is the resource server that checks access tokens. An authorization server signs users in and issues those tokens. WorkOS and Auth0 both sell the second role, so you do not have to build OAuth yourself.

At a glance

MAU means monthly active users.

Where WorkOS is stronger

Generous free sign-ins. WorkOS's pricing page says "First 1 million monthly active users free" for AuthKit. Each extra million costs $2,500 per month. For a consumer-scale MCP server, that free tier is large.

Keep the login you already have. The AuthKit MCP docs say that if "you already have an existing authentication system," you can use Standalone Connect. AuthKit sends users to your app's login page, your app signs them in, and then it calls AuthKit's completion API. Your users stay where they are.

Clear resource-server steps. The docs walk through adding your MCP endpoint as a resource indicator, so tokens carry an audience (aud) that matches your server. Your 401 response then includes a WWW-Authenticate header with a resource_metadata URL. This is the pattern the MCP authorization spec expects.

Cross App Access. WorkOS lists Cross App Access as "available in early access." It lets a user signed in to one app reach another app's MCP server through their identity provider, without a separate OAuth flow. WorkOS notes it is not supported with Standalone MCP Auth. See enterprise-managed authorization.

Where Auth0 is stronger

Downstream API access. Many MCP servers must call other services as the user. Auth0's overview says Token Vault "handles these integrations by managing token issuance, storage, rotation, and revocation for external APIs," naming Google, Microsoft, Jira and Notion. For your own APIs, Auth0 "implements the On-Behalf-Of Token Exchange," swapping the client's token for a short-lived one scoped to the internal API. That helps you avoid token passthrough.

Registration choice and guidance. Auth0's registration guide covers manual, CIMD and DCR registration. It says: "For production MCP deployments, we recommend using CIMD registration." That matches the 2026-07-28 spec, which deprecated DCR in favor of CIMD.

Identity provider reach. The overview says users can sign in through providers such as Okta, Entra ID, Ping or Google Workspace. If your company already runs Okta, Auth0 sits in the same family.

SDKs. Auth0 links a JavaScript SDK (auth0-auth-js) and a Python SDK (auth0-api-python) for MCP servers.

Pricing

Prices from each vendor's pricing page on 28 October 2026. Both change with volume, so model your own users.

WorkOS (pricing):

• AuthKit: free to 1 million MAUs, then $2,500 per month per extra million.
• SSO: $125 per connection per month for 1 to 15 connections, lower above that.
• Audit Logs: $125 per month per SIEM connection, $99 per month per million retained events.
• The page does not list a separate price for MCP Auth or Connect, and says "only production environments are billed."

Auth0 (pricing):

• Free: $0, "up to 25,000 monthly active users," with "Secure Agentic AI workflows" listed.
• Essentials: from $35 per month (B2C) or $150 (B2B) at 500 MAUs.
• Professional: from $240 per month (B2C) or $800 (B2B) at 500 MAUs.
• Token Vault: 2 connections on Free, 3 on Essentials and Professional, plus add-ons.
• An Auth0 for AI Agents add-on "adds 50% to the base price (rounded up to the dollar)."

The pricing page we opened did not name "Auth for MCP" as a line item. The closest item is the Auth0 for AI Agents add-on, priced only on Essentials and Professional at 50% of the plan's base price; it includes "Unlimited Token Vault" and "All forms of CIBA." Ask Auth0 which plan your MCP use needs.

Security and admin controls

Shared basics. Both issue tokens tied to your MCP server as the audience, publish discovery metadata and support CIMD, which the spec now prefers. Your server still has to verify issuer, audience and expiry on every request.

WorkOS. The WorkOS security page says it is "SOC 2 Type 2 certified" and "GDPR & CCPA compliant," and that it can sign HIPAA business associate agreements on enterprise plans. Audit Logs with SIEM streaming are a paid add-on.

Auth0. Token Vault keeps third-party tokens out of your server code, and On-Behalf-Of exchange limits each downstream token's scope. Both reduce the blast radius if your MCP server is compromised.

One caution on WorkOS. CIMD is "off by default." Turn it on, or newer clients may fall back to DCR, which the spec has deprecated.

Which to choose

Pick WorkOS if:

• You expect many users and want AuthKit's 1 million free MAUs.
• You have your own login and want only the MCP OAuth layer (Standalone Connect).
• You already use WorkOS for enterprise SSO.

Pick Auth0 if:

• Your MCP server calls Google, Microsoft, Jira or similar APIs for each user.
• You need On-Behalf-Of exchange to reach internal APIs safely.
• Your company already standardizes on Okta or Auth0.

Compare a third option if you want a smaller vendor with bring-your-own-auth pricing. See Scalekit vs WorkOS.

Next step

Choosing the auth vendor is one part of shipping a remote MCP server. eSEOspace wires OAuth into servers through our MCP development service. Browse more MCP comparisons or read MCP authentication and OAuth.

Frequently asked questions