Auth0 vs Keycloak for Solo Developers

Quick Comparison

Auth0 Overview

Auth0 is Okta's managed identity platform. Social logins, passwordless, MFA, SAML SSO, SCIM provisioning, machine-to-machine tokens, RBAC. The full enterprise auth stack, hosted and maintained by Okta. You configure it through a dashboard, connect your app via SDK, and Auth0 handles the rest.

The Universal Login page runs on Auth0's domain. Users authenticate there and your app gets tokens. Actions let you hook into any step of the auth flow with serverless code. The documentation is excellent and covers virtually every framework and language.

For a B2B project where a client required Okta SAML SSO, Auth0 was the fastest path. Configuring the SAML connection took an afternoon. Everything after that was managed by Auth0.

Keycloak Overview

Keycloak is an open-source identity and access management server, backed by Red Hat. It provides social login, SAML, OpenID Connect, LDAP/AD integration, user federation, fine-grained authorization, and an admin console. It's the same class of tool as Auth0, but you host and manage it yourself.

The admin console is a full-featured web UI for managing realms, clients, users, roles, and identity providers. Keycloak supports themes for customizing login pages, and the extension system (SPIs) lets you add custom behavior. It's Java-based and runs as a standalone server or in a container.

I deployed Keycloak in Docker for a project that needed SSO across multiple internal apps. The admin console is powerful, the OIDC/SAML support is thorough, and it handled user federation from an existing LDAP directory. But getting it configured and running took a full weekend.

Key Differences

Managed vs self-hosted. Auth0 is SaaS. You pay, they run it. Uptime, security patches, scaling, and backups are their problem. Keycloak is a Java server you deploy and operate. You handle hosting, updates, database backups, and high availability. For a solo developer, operating Keycloak is a serious commitment.

Setup time. Auth0 takes an hour or two to configure from scratch. Keycloak takes significantly longer. You need to deploy the server, configure the database, set up realms and clients, configure social providers, and customize the login theme. A production-ready Keycloak deployment takes a weekend at minimum.

Cost. Auth0's free plan now covers up to 25,000 monthly active users, a generous ceiling that many solo projects never cross. Past that, B2C Essentials starts at $35/month for 500 MAU and climbs by tier as you grow. Keycloak is free software. You pay only for hosting, which could be as cheap as $5 to $10/month on a small VPS. If you're running a server anyway, Keycloak's marginal cost is nearly zero. Over a year, that savings adds up compared to Auth0 once you outgrow the free tier.

Feature parity. Keycloak and Auth0 are roughly equivalent in features. Both handle SAML, OIDC, MFA, social login, user federation, and role-based access. Keycloak actually has some features Auth0 charges premium prices for, like fine-grained authorization policies and LDAP federation. The feature gap is small.

Operational burden. This is the deciding factor. Auth0 requires zero ops work. Keycloak requires you to manage a Java application server, a PostgreSQL database, TLS certificates, backups, and version upgrades. For a solo developer who already has a server to manage, adding Keycloak is doable. For someone who wants to focus purely on product work, Auth0 is safer.

SDK and developer experience. Auth0 has polished SDKs for every major framework with getting-started guides. Keycloak has adapters for Java frameworks and generic OIDC client libraries for everything else. The developer experience with Auth0 is smoother. Keycloak's documentation is thorough but more enterprise-oriented.

By the Numbers (2026)

Here is where the two tools actually stand as of late May 2026, checked against the vendor pages and the public repository.

Auth0 (managed SaaS, by Okta)

• Free plan covers up to 25,000 monthly active users at $0, no credit card required, identical limit for B2C and B2B workspaces. This is a real increase over the old 7,500 MAU ceiling that older articles still quote.
• B2C Essentials starts at $35/month for 500 MAU and scales by tier: roughly $70 at 1,000 MAU, $175 at 2,500 MAU, and $350 at 5,000 MAU.
• B2C Professional starts at $240/month for 500 MAU for teams that need advanced features.
• B2B Essentials is a separate ladder that starts at $150/month for 500 MAU.
• Annual billing is charged at 11 times the monthly price, so committing for a year is effectively one month free.

Keycloak (open source, backed by Red Hat)

• Latest release is 26.6.2, published May 19, 2026. The 26.6.0 feature release landed April 8, 2026 and added a JWT authorization grant, federated client authentication, supported Workflows, organization groups, and zero-downtime patch releases.
• Written in Java and now runs on OpenJDK 25. Licensed under Apache 2.0, so there is no per-user or per-MAU fee, ever.
• 34,623 GitHub stars and 8,404 forks on the keycloak/keycloak repository, reflecting a large and active community.
• The browser client adapter, keycloak-js, pulled 822,914 npm downloads in the last week (May 21 to May 27, 2026), a useful proxy for how widely it is wired into front-end apps.
• Cadence is four minor releases per year with a major version every two to three years, so you will be applying updates on a predictable schedule.

Real Cost at Solo-Dev Scale

Numbers in a table are abstract until you map them to your own app, so here is a worked example for a typical solo-developer product.

Assumptions: a consumer-facing B2C app that grows to 8,000 monthly active users over its first year, hosted on a small VPS you are already paying for. We will compare staying on Auth0 against self-hosting Keycloak.

Auth0 path. At 8,000 MAU you are still comfortably under the free 25,000 ceiling, so Auth0 costs $0/month at this scale. The free tier absorbs the entire first year. You would only start paying once you cross 25,000 MAU, at which point you move onto a paid B2C ladder that starts at $35/month for the first 500 paid MAU and steps up from there. For a great many solo apps, that day never comes.

Keycloak path. Keycloak's software cost is $0 forever. The real cost is the VPS and your time. A box big enough to run Keycloak plus its PostgreSQL database comfortably runs in the $10 to $20/month range, but if you are already running a server for the app, the marginal infrastructure cost is close to zero. The hidden line item is operations: TLS renewal, database backups, and applying four minor releases per year, each of which you test and roll out yourself.

The honest verdict on cost. With Auth0 raising its free tier to 25,000 MAU, the old money argument for Keycloak has largely collapsed for solo developers. At 8,000 MAU both options are effectively free, and Auth0 is free without any ops burden. Keycloak only wins on cost once you are well past 25,000 MAU and the per-tier Auth0 bill starts to matter, or when you need a feature Auth0 gates behind an enterprise plan such as deep LDAP federation. Below that threshold you are paying for Keycloak in weekends, not dollars.

When to Choose Auth0

• You don't want to manage auth infrastructure
• Quick setup matters more than long-term cost savings
• You need polished SDKs for JavaScript, Python, or mobile frameworks
• You want managed uptime and security patching
• You're building consumer-facing apps where downtime is unacceptable

When to Choose Keycloak

• You're already managing servers and are comfortable with ops work
• You want enterprise-grade auth features without per-user pricing
• LDAP or Active Directory integration is a requirement
• You need complete control over your identity infrastructure
• Long-term cost savings outweigh short-term convenience

The Verdict

For solo developers, Auth0 is usually the better choice. Keycloak is a powerful identity platform, but operating it is a full-time concern. Deploying it, keeping it updated, backing up the database, monitoring uptime. That's time you're not spending on your product. Auth0 handles all of that for a monthly fee.

Keycloak makes sense if you're already running infrastructure and are comfortable with server management. If you have a VPS for your app and adding a Docker container is trivial, Keycloak gives you enterprise auth for almost free. It's the choice for infrastructure-savvy developers who value ownership over convenience.

My recommendation: unless you genuinely enjoy running servers and have the time to maintain Keycloak, use Auth0. The managed service lets you focus on building your product. If you're the kind of developer who runs their own K8s cluster for fun, Keycloak is your auth solution.

Sources

All figures checked on May 28, 2026.

• Auth0 pricing tiers and free-tier MAU limit: auth0.com/pricing
• Keycloak repository, stars, forks, and primary language: github.com/keycloak/keycloak
• Keycloak latest release (26.6.2) and version data: endoflife.date/keycloak
• Keycloak 26.6.0 feature release and date: keycloak.org/2026/04/keycloak-2660-released
• keycloak-js weekly npm download count: npmjs.com/package/keycloak-js (download stats via the npm registry downloads API)