~/CLIRank

Best Authentication & Identity APIs for AI Agents in 2026

Identity management, OAuth, verification, and bot protection APIs. Secure your app without building auth from scratch. Below: the top 10 Authentication & Identity APIs by CLIRank score, the independent rubric for how well an API actually works with AI coding agents like Claude Code and Cursor.

1
Firebase Authentication10/10Identity Platform

Google-backed auth for mobile and web with social login support.

Best for: mobile apps

CLI relevance
7
Quality
10
authenticate usersmanage user accountsverify phone numbersimplement sso
npm install firebase
2
Supabase Auth10/10Identity Platform

Open-source auth with row-level security tied to PostgreSQL.

Best for: Postgres-first apps

CLI relevance
10
Quality
10
authenticate usersmanage user accountsimplement ssomanage row-level security
npm install @supabase/supabase-js
3
Google OAuth 2.010/10OAuth Providers

Google sign-in and OAuth 2.0 authorisation for apps.

Best for: Most widely used social login - users expect it

CLI relevance
6
Quality
10
authenticate usersauthorise api accessmanage tokensget user profiles
npm install googleapis
4
AWS Cognito9/10Identity Platform

User sign-up, sign-in, and access control for AWS apps.

Best for: Cheapest auth at scale - 50k MAU free, then pennies after

CLI relevance
10
Quality
9
authenticate usersmanage user poolsimplement ssoenforce mfa
npm install @aws-sdk/client-cognito-identity-provider
5
Auth0 API8/10Identity Platform

Authentication, authorisation, and user management for apps.

Best for: enterprise apps

CLI relevance
10
Quality
9
authenticate usersmanage user accountsimplement ssomanage roles
npm install auth0
6
Better Auth8/10Auth Framework

Framework-agnostic TypeScript auth library. Self-hosted, open-source, with built-in support for email/password, social login, 2FA, and session management.

Best for: self-hosted requirements

CLI relevance
9
Quality
7
email-password-authsocial-logintwo-factor-authsession-management
npm install better-auth
7
Okta API6/10Identity Platform

Enterprise identity management, SSO, and MFA.

Best for: Enterprise SSO standard - supports every identity provider

CLI relevance
8
Quality
7
authenticate usersimplement ssomanage user lifecycleenforce mfa
npm install @okta/okta-sdk-nodejs
8
Clerk API4/10Identity Platform

Drop-in auth components with user management and session handling.

Best for: Next.js apps

CLI relevance
9
Quality
4
authenticate usersmanage user accountsimplement ssomanage organisations
npm install @clerk/clerk-sdk-node
9
Twilio Verify/10Verification

Phone verification via SMS, voice, email, and TOTP.

Best for: Simplest phone verification API - OTP via SMS, voice, email

CLI relevance
8
Quality
4
verify phone numberssend otp codesverify email addresses
10
reCAPTCHA API/10Bot Protection

Protect sites from spam and abuse with CAPTCHA challenges.

Best for: Free for most use cases - up to 1M assessments/month

CLI relevance
5
Quality
4
verify humansblock botsassess risk

Showing top 10 of 12 Authentication & Identity APIs. Browse all.

Frequently asked questions

What makes an Authentication & Identity API "agent-friendly"?

For AI coding agents, the highest-impact signals are: an official SDK on npm or PyPI, environment variable authentication (no browser OAuth flow), JSON responses that parse cleanly, machine-readable pricing, and reasonable rate limits for scripted use. APIs missing more than two of these are painful for agents to use reliably.

How do you score Authentication & Identity APIs?

Each API is rated on 8 signals worth 1-2 points each (11 raw, normalised to 10). The full rubric: official SDK (+2), env var auth (+2), headless compatible (+2), CLI tool (+1), JSON response (+1), curl/CLI docs examples (+1), reasonable rate limits (+1), machine-readable pricing (+1). The top-scoring API in this category right now is Firebase Authentication at 10/10.

Why isn't [my favourite API] on this list?

This list shows the top 10 Authentication & Identity APIs by score. The full ranking includes 12 APIs in this category. If yours is missing entirely, submit it at clirank.dev/submit - it gets auto-scored and added if it clears the threshold.

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