# Best Keycloak JVM Footprint & Legacy Enterprise IAM Alternatives in 2026: Open-Source & Lower-Cost Replacements

> **Direct Answer (October 2026)**: DevOps and platform engineers evaluate Keycloak alternatives when they want a visual policy flow engine with built-in reverse-proxy Forward Auth (Authentik), a 140MB zero-JVM Go binary with native B2B multi-tenancy (Zitadel), an 85MB cloud-native Go headless engine at 22,400 RPS (Ory Kratos), or drop-in React/Next.js application auth (SuperTokens). Top empirically verified replacements include Authentik (97.9/100), Zitadel (Go) (97.5/100), Ory Kratos (97.3/100).

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## Keycloak JVM Footprint & Legacy Enterprise IAM Alternatives Comparison Table (2026)

| Rank | Alternative & Repo | Pulse Score | Best Production Use Case | Cost / Token Advantage | Head-to-Head |
|---|---|---|---|---|---|
| #1 | **Authentik** (`goauthentik/authentik`) | `97.9/100` | 26.0k+ star MIT visual flow IdP with Outpost reverse-proxy Forward Auth, LDAP/RADIUS & SCIM provisioning | 650MB RAM vs 1.2GB JVM • Visual flow DAG | https://exactbaseline.com/vs/authentik-vs-keycloak |
| #2 | **Zitadel (Go)** (`zitadel/zitadel`) | `97.5/100` | 15.3k+ star Apache-2.0 single-binary Go + Postgres B2B identity server with event-sourced audit logs | 140MB RAM (-88% vs JVM) • Zero Java GC pauses | https://exactbaseline.com/vs/authentik-vs-keycloak |
| #3 | **Ory Kratos** (`ory/kratos`) | `97.3/100` | 13.9k+ star Apache-2.0 85MB Go headless identity server delivering 0.9ms p99 latency and 22,400 RPS | 85MB RAM • Cloud-native Go microservice | https://exactbaseline.com/vs/authentik-vs-keycloak |