Claude API Single Sign-On Integration Guide

Does the Claude API support single sign-on?

Anthropic's Claude API does not have a native single sign-on (SSO) layer in the way a SaaS dashboard application does. API access is authenticated with a static API key, not with an OIDC or SAML identity assertion. If you're searching for "claude api single sign on integration" because you want your engineers to log in with Okta, Google Workspace, or Azure AD and automatically get scoped access to Claude, you need to build or buy a layer that sits between your identity provider and the raw API key.

That layer typically does three things: it authenticates the human through your existing SSO provider, it maps that identity to a permission level (admin, developer, read-only usage viewer), and it issues or proxies a credential that the user's code can actually call against. This article walks through why raw API keys and SSO don't mix well, the patterns that do work, and how a service like SubToAPI solves the team-access part of this problem without you having to write custom SAML glue code.

Why raw API keys break the SSO model

SSO exists to centralize authentication and authorization for humans logging into web apps. An API key is a long-lived machine credential, usually shared across a codebase, CI pipeline, or multiple developers. These two concepts don't map cleanly onto each other:

• No per-user identity in the key itself. A single Anthropic API key doesn't know which developer is making a request, so you can't apply SSO group policies (e.g., "only the ML team can use Claude") at the key level.
• Rotation is manual. If someone leaves the company, you have to manually revoke and redistribute the key to everyone still using it — SSO is supposed to make offboarding instant.
• No audit trail by user. When five developers share one key, your logs show one identity, not five, which defeats the purpose of identity-based access control.
• Key sprawl. Without a central broker, keys end up pasted in .env files, Slack messages, and CI secrets with no single point of revocation.

If your actual goal is "give my SSO-authenticated engineers individually traceable, revocable access to Claude," the fix isn't to bolt SAML onto Anthropic's key system — it's to put a key-management and proxy layer in front of it.

Pattern 1: Build an internal broker service

You can build this yourself: an internal service authenticates users via your SSO provider (using a library like Passport.js, NextAuth, or your IdP's SDK), checks their group membership, and then either returns a short-lived token or proxies the Claude request on the user's behalf using a backend-held master key.

// Simplified internal broker example
app.post('/internal/claude/messages', requireSSOSession, async (req, res) => {
  const user = req.ssoUser; // populated by your SSO middleware
  if (!user.groups.includes('ai-access')) {
    return res.status(403).json({ error: 'not authorized' });
  }

  const response = await fetch('https://api.anthropic.com/v1/messages', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.ANTHROPIC_MASTER_KEY,
      'anthropic-version': '2023-06-01',
      'content-type': 'application/json'
    },
    body: JSON.stringify(req.body)
  });

  logUsage(user.email, req.body); // per-user audit trail
  res.json(await response.json());
});

This works, but you now own authentication middleware, rate limiting, per-user logging, billing attribution, and key rotation. For a small team that's a lot of plumbing for what should be an infrastructure detail.

Pattern 2: Use a managed key-and-seat layer

The alternative is to use a platform that already handles team-level access control and issues scoped application keys, so you only need SSO for your own product login — not for every Claude call. This is the model SubToAPI is built around: instead of one shared Anthropic key, you get a dashboard where you invite teammates as seats, each person (or each service) gets its own sub_live_... key, and you can revoke individual keys instantly without touching anyone else's access.

This doesn't give you literal SAML-based SSO into the Claude API itself (there's no such standard to plug into), but it solves the actual business problem behind the search query:

• Team seats instead of a shared secret. Each developer or environment gets a distinct key under Solo, Team, or Scale plans — see /pricing.
• Instant revocation. Remove a seat and that key stops working immediately, which is the behavior people expect from SSO-driven offboarding.
• Usage visibility per key. You can see which key — and therefore which person or service — is driving token usage and spend.
• One dashboard, not five shared .env files. New hires get a key issued to them directly instead of inheriting a key that's been copy-pasted for two years.

If your organization already uses SSO for your main product and you want the same "centralized access, individual accountability" behavior for Claude usage, pairing your SSO-gated internal tools with SubToAPI-issued per-user keys gets you there without custom SAML integration work.

Getting started

1. Sign up at /signup and create your workspace.
2. Invite teammates as seats and let each one generate their own key from the dashboard.
3. Replace any shared Anthropic key in your codebase with the per-user SubToAPI key, following /docs/quickstart.
4. Use /docs/messages for the core request format, and /docs/streaming or /docs/tools if your app needs streaming responses or tool use.

Your existing SSO layer continues to control who can log into your internal admin panel or dashboard; SubToAPI controls who holds a valid, individually-scoped key to actually call Claude.

questions

Does Anthropic offer native SAML or OIDC login for the Claude API? No. The Claude API authenticates with API keys, not identity federation protocols. SSO has to be implemented at a layer you control or through a provider that manages per-user key issuance.

Can I give each developer their own Claude API key instead of sharing one? Yes, and it's the recommended approach. Services like SubToAPI let you issue a distinct key per seat so usage and revocation are tracked individually rather than against one shared secret.

What's the simplest way to add "SSO-like" access control to Claude usage? Keep your existing SSO for logging into your internal tools, then use a key-management layer (self-built proxy or a platform like SubToAPI) to turn each authenticated session into a scoped, revocable API credential.