Auth0 vs Lucia for Solo Developers

Quick Comparison

Auth0 Overview

Auth0 is the enterprise-grade identity platform owned by Okta. It handles authentication for you as a managed service: social logins, passwordless, MFA, SAML SSO, machine-to-machine tokens, and role-based access control. If there's an auth scenario, Auth0 supports it.

The Universal Login page handles authentication on Auth0's domain, which is a genuine security advantage. Credentials never touch your server. The Actions system lets you customize login flows with serverless hooks, enrich tokens, and connect external services. Documentation covers every framework and language.

I used Auth0 for a project that needed Google Workspace SSO for a B2B client. The SAML connection took about an afternoon to configure, but once working, it handled everything without me writing token verification code. For enterprise requirements, Auth0 delivers.

Lucia Overview

Lucia is an open-source auth library that runs in your own codebase. It's not a managed service. You install it, configure it with your database adapter, and build your auth flows using the functions it provides. Session management, cookie handling, and token generation are covered. Everything else, you build.

The philosophy is intentional: Lucia gives you the building blocks and stays out of your way. You control the database schema, the login forms, the session logic, and the entire auth flow. There's no external dashboard, no vendor dependency, and no monthly bill. Your auth lives in your codebase alongside your application.

I built a small SaaS with Lucia where I needed custom session logic that no managed service would let me implement. Having the auth layer as a library meant I could extend it exactly how I needed. It took longer to set up than a managed solution, but the result was exactly what I wanted.

Key Differences

Setup time. Auth0 can be configured in 30-60 minutes with their guides. You create an application, configure callbacks, install the SDK, and you're authenticating users. Lucia takes longer because you're building the auth flow yourself: registration forms, login handlers, session middleware, password hashing. Expect a few hours to a full day for a complete auth setup with Lucia.

Managed vs self-hosted. Auth0 runs the infrastructure. They handle security patches, scaling, uptime, and compliance certifications. Lucia runs wherever your app runs. You're responsible for keeping dependencies updated, handling security patches, and ensuring your session store is reliable. This is the fundamental tradeoff.

Cost. Auth0 gives you 7,500 MAU free, then $35/month for Essential. At scale, it gets expensive. Lucia is free forever. No MAU limits, no monthly bills, no usage tiers. If you're bootstrapping and every dollar matters, Lucia's cost advantage is significant.

Customization. Lucia gives you complete control. Custom session lengths, custom token payloads, custom database schemas, custom login flows. Auth0 offers customization through Actions and Rules, but you're working within their system. If your auth needs are unusual, Lucia won't fight you.

Social logins. Auth0 makes social login trivial. Toggle a switch in the dashboard, enter your OAuth credentials, and Google/GitHub/Apple sign-in works. With Lucia, you implement OAuth flows yourself using complementary libraries like Arctic. It works, but it requires more code and more testing.

Enterprise features. Auth0 has SAML SSO, SCIM provisioning, organizations, and compliance certifications out of the box. Lucia has none of this. If you're building B2B software where customers need enterprise SSO, Auth0 solves that. With Lucia, you'd be building SAML support from scratch, which is not advisable.

When to Choose Auth0

• You need enterprise SSO (SAML, SCIM) for B2B customers
• You want auth managed by someone else so you can focus on features
• Social login setup should be checkbox-level easy
• Security compliance (SOC 2, HIPAA) is a requirement
• You're using a framework Auth0 has official SDKs for

When to Choose Lucia

• You want zero recurring costs for authentication
• You need full control over your auth logic and database schema
• You're building something with non-standard session requirements
• Vendor lock-in is a concern and you want to own every line of auth code
• You enjoy building infrastructure and treat auth as a learning opportunity

The Verdict

For solo developers shipping a product fast, Auth0 is the pragmatic choice. The managed service handles security, scaling, and social logins so you can focus on building features. The free tier is generous enough for most early-stage projects.

For solo developers who want ownership and control, Lucia is the principled choice. No vendor dependency, no monthly costs, and complete flexibility. But you're trading convenience for control, and the initial setup time is real.

My recommendation: if you're building a product you want to ship quickly, use Auth0 or another managed service. If you're building something where you need deep auth customization or you philosophically prefer owning your stack, Lucia rewards the extra effort. Choose based on whether you value speed or control more.