Authentication Alternatives in 2025: A Developer's Guide Beyond Auth0

TL;DR

This article examines practical authentication alternatives to Auth0 for developers, comparing both commercial solutions (Okta, Microsoft Entra ID, SSOJet) and open-source options (Keycloak, Ory, Supertokens). We analyze technical implementation details, deployment models, developer experience, and architectural considerations to help you make an informed decision based on your specific development requirements.

Table of Contents

• Introduction
• Why Developers Seek Auth0 Alternatives
• Commercial Authentication Solutions
• Open-Source Authentication Frameworks
• Technical Feature Comparison
• Implementation Strategy
• Conclusion

Introduction

Authentication sits at the foundation of application security, yet implementing it correctly remains one of the most challenging aspects of modern development. As data breaches become increasingly common and regulatory requirements grow more complex, choosing the right authentication solution has become a critical architectural decision.

While Auth0 has positioned itself as a leading identity platform, its pricing structure, technical constraints, or strategic direction may not align with every development team's requirements. In this developer-focused guide, we'll explore the technical landscape of Auth0 alternatives, examining implementation details, architectural considerations, and developer experience across various solutions.

Why Developers Seek Auth0 Alternatives

From a developer perspective, several factors drive the search for Auth0 alternatives:

// Example of Auth0 pricing pain point
// With per-active-user pricing at $0.XX/user/month
// An app with 100,000 users but low engagement:
const monthlyUsers = 100000;
const auth0PricePerUser = 0.XX; // Placeholder price
const monthlyAuth0Cost = monthlyUsers * auth0PricePerUser;
// Cost scales directly with user count regardless of actual authentication activity

Key technical drivers include:

• Developer Control: Need for greater customization, self-hosting capabilities, or direct access to authentication libraries
• Architectural Constraints: Microservices architectures that require more flexible identity components
• Technical Debt: Legacy system integration requirements that demand specialized connectors
• Deployment Models: Requirements for on-premises, air-gapped, or hybrid deployment scenarios

Commercial Authentication Solutions

Okta

Okta's enterprise identity platform offers robust capabilities that extend beyond Auth0 (which it acquired).

Technical Implementation Details:

// Example Okta Authentication Flow
import { OktaAuth } from '@okta/okta-auth-js';

const oktaAuth = new OktaAuth({
  issuer: 'https://{yourOktaDomain}/oauth2/default',
  clientId: '{clientId}',
  redirectUri: window.location.origin + '/login/callback',
  scopes: ['openid', 'profile', 'email']
});

// Initiate authentication
async function login() {
  try {
    await oktaAuth.signInWithRedirect();
  } catch (error) {
    console.error('Authentication failed:', error);
  }
}

Architecture Considerations:

• Enterprise-grade infrastructure with extensive API access
• Comprehensive workforce identity capabilities
• Higher implementation complexity requiring specialized knowledge

Microsoft Entra ID (formerly Azure AD)

Microsoft's identity solution offers deep integration with Azure services.

Technical Implementation Details:

// Microsoft MSAL Authentication Example
import * as msal from '@azure/msal-browser';

const msalConfig = {
  auth: {
    clientId: 'your-client-id',
    authority: 'https://login.microsoftonline.com/your-tenant-id',
    redirectUri: window.location.origin
  }
};

const msalInstance = new msal.PublicClientApplication(msalConfig);

async function signIn() {
  try {
    const loginResponse = await msalInstance.loginPopup({
      scopes: ["user.read"]
    });
    return loginResponse.account;
  } catch (err) {
    console.error("Login failed:", err);
  }
}

Architecture Considerations:

• Optimized for Microsoft ecosystem integration
• Powerful capabilities for hybrid cloud environments
• Requires understanding of Microsoft's identity concepts and terminology

SSOJet

An emerging solution tailored specifically for SaaS applications.

Technical Implementation Details:

// SSOJet Implementation Example
import { SSOJetClient } from '@ssojet/client';

const ssojet = new SSOJetClient({
  clientId: 'your-client-id',
  domain: 'auth.yourdomain.com',
  redirectUri: window.location.origin + '/callback'
});

function authenticate() {
  ssojet.authorize({
    responseType: 'code',
    scope: 'openid profile email'
  });
}

Architecture Considerations:

• API-first design optimized for developer workflows
• Purpose-built for SaaS authentication patterns
• Modern implementation with minimal configuration overhead

Discussion Point:
What authentication flow patterns have you implemented in production? How did you handle token refresh strategies and session management across distributed services?

Open-Source Authentication Frameworks

Keycloak

Red Hat's open-source identity solution offers enterprise features with full source access.

Technical Implementation Details:

// Keycloak JS Adapter Example
import Keycloak from 'keycloak-js';

const keycloak = new Keycloak({
  url: 'https://keycloak-server/auth',
  realm: 'your-realm',
  clientId: 'your-client-id'
});

keycloak.init({ onLoad: 'login-required' })
  .then(authenticated => {
    if (authenticated) {
      // Store tokens and setup refresh
      localStorage.setItem('token', keycloak.token);
      localStorage.setItem('refresh-token', keycloak.refreshToken);

      // Setup automatic token refresh
      setInterval(() => {
        keycloak.updateToken(70)
          .catch(() => keycloak.login());
      }, 60000);
    } else {
      console.error('Authentication failed');
    }
  }).catch(error => {
    console.error('Initialization failed:', error);
  });

Architecture Considerations:

• Self-hosted with complete control over identity data
• Extensive customization capabilities through themes and SPIs
• Requires significant expertise to deploy and maintain securely

Ory

A cloud-native, API-first identity system designed for microservices architectures.

Technical Implementation Details:

// Ory Kratos Example (Go)
package main

import (
    "github.com/ory/kratos-client-go/client"
    "github.com/ory/kratos-client-go/client/public"
)

func main() {
    // Initialize the Kratos client
    c := client.NewHTTPClientWithConfig(
        nil,
        &client.TransportConfig{
            Schemes:  []string{"https"},
            Host:     "identity.example.com",
            BasePath: "/",
        },
    )

    // Get self-service registration flow
    params := public.NewInitializeSelfServiceRegistrationFlowParams()
    flow, err := c.Public.InitializeSelfServiceRegistrationFlow(params)
    if err != nil {
        // Handle error
    }

    // Use flow.Payload.ID to render registration form
}

Architecture Considerations:

• Modular components for different identity functions (Kratos, Hydra, Oathkeeper)
• API-first design ideal for microservices and cloud-native applications
• Lightweight with minimal dependencies

Supertokens

A developer-friendly, customizable authentication system focusing on modern applications.

Technical Implementation Details:

// SuperTokens React Example
import SuperTokens from "supertokens-auth-react";
import Session from "supertokens-auth-react/recipe/session";
import EmailPassword from "supertokens-auth-react/recipe/emailpassword";

SuperTokens.init({
  appInfo: {
    appName: "Your App Name",
    apiDomain: "https://api.yourapp.com",
    websiteDomain: "https://yourapp.com",
    apiBasePath: "/auth",
    websiteBasePath: "/auth"
  },
  recipeList: [
    EmailPassword.init(),
    Session.init({
      tokenTransferMethod: "cookie",
      cookieSecure: true
    })
  ]
});

// In your API
import { verifySession } from "supertokens-node/recipe/session/framework/express";

app.get("/api/user/data", verifySession(), async (req, res) => {
  const userId = req.session.getUserId();
  // Fetch and return user data
});

Architecture Considerations:

• Self-hosting capability with commercial support options
• Optimized for modern frontend frameworks (React, Angular, Vue)
• Excellent developer experience with comprehensive SDKs

Technical Feature Comparison

When evaluating authentication solutions, these technical details matter most to developers:

Authentication Protocol Support

Solution	OAuth 2.0	OIDC	SAML	Custom JWT	WebAuthn
Okta	✅	✅	✅	✅	✅
MS Entra ID	✅	✅	✅	✅	✅
SSOJet	✅	✅	✅	✅	✅
Keycloak	✅	✅	✅	✅	✅
Ory	✅	✅	❌	✅	✅
Supertokens	✅	✅	❌	✅	✅

Developer Experience

The quality of SDKs, documentation, and API design varies significantly:

• Documentation Quality: SSOJet, FusionAuth, and Auth0 lead with comprehensive developer guides
• SDK Availability: Commercial solutions typically provide more framework-specific SDKs
• API Design: Ory, Supertokens, and SSOJet feature modern, RESTful API designs
• Local Development: Open-source solutions enable better local development workflows

Deployment Flexibility

# Docker Compose example for Keycloak deployment
version: '3'

services:
  postgres:
    image: postgres:13
    volumes:
      - postgres_data:/var/lib/postgresql/data
    environment:
      POSTGRES_DB: keycloak
      POSTGRES_USER: keycloak
      POSTGRES_PASSWORD: password

  keycloak:
    image: quay.io/keycloak/keycloak:latest
    command: start-dev
    environment:
      KC_DB: postgres
      KC_DB_URL: jdbc:postgresql://postgres:5432/keycloak
      KC_DB_USERNAME: keycloak
      KC_DB_PASSWORD: password
      KEYCLOAK_ADMIN: admin
      KEYCLOAK_ADMIN_PASSWORD: admin
    ports:
      - "8080:8080"
    depends_on:
      - postgres

volumes:
  postgres_data:

The right deployment model depends on your infrastructure requirements:

• Cloud-Only: Simplest to implement but with least control
• Self-Hosted: Maximum control but higher operational overhead
• Hybrid Options: Flexibility but increased complexity
• Container-Friendly: Most modern solutions are containerized

Implementation Strategy

When implementing an Auth0 alternative, follow these best practices:

1. Abstraction Layer: Create an authentication service abstraction

   // auth-service.ts
   interface AuthProvider {
     login(credentials: any): Promise;
     logout(): Promise;
     getUser(): Promise;
     refreshToken(): Promise;
     isAuthenticated(): boolean;
   }

   class KeycloakAuthProvider implements AuthProvider {
     // Implementation details
   }

   // This allows you to swap providers without changing application code

1. Token Management: Implement secure token storage and refresh
2. Role-Based Authorization: Design consistent permission models
3. Multi-Environment Setup: Configure for development, testing, and production
4. Monitoring: Implement authentication failure tracking

Conclusion

The ideal Auth0 alternative depends entirely on your specific development requirements, technical capabilities, and strategic direction. For teams prioritizing developer experience and modern API design, options like SSOJet, FusionAuth, or Supertokens may be optimal. If maximum control and customization are priorities, Keycloak and Ory provide powerful open-source foundations.

When making your selection, prioritize solutions that offer the authentication features you need today while providing the flexibility to evolve as security requirements change. Remember that authentication isn't just a technical checkbox—it's a foundational component of your application's security architecture.

What authentication challenges is your team facing? Have you implemented any of these Auth0 alternatives in production? Share your experiences in the comments below.

This article was adapted from my original blog post. Read the full version here: Beyond Auth0: A Comprehensive Guide to Authentication Alternatives in 2025