sizing
Keycloak Memory Usage and Heap Sizing Explained
Keycloak hardware requirements explained: RAM baselines, JVM heap and container limits, Infinispan session ca…
Keycloak Ops — Realms, sessions and proxies in production.
Realms, sessions and proxies in production.
Keycloak Ops
Independent · 2026
Independent · 2026
troubleshooting
Keycloak Behind a Reverse Proxy: Fix 403 and Hostname Errors
Why Keycloak returns 403 behind a proxy, rejects redirect URIs, and issues tokens with the wrong issuer, and the exact options that resolve each case.
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comparisons
Keycloak vs authentik vs Authelia: What to Self-Host
A protocol, architecture and footprint comparison of three self-hosted identity servers, and the deployment s…
fundamentals
Keycloak Realms Explained: Clients, Roles and Tokens
What a Keycloak realm isolates, when to use one or several realms, and how clients, roles, scopes, sessions a…
Start here
Four guides, in the order the questions usually arrive: how to structure a realm, why nothing works behind the proxy, how much memory the thing actually needs, and whether Keycloak is the right choice at all.
- Realms, clients and token design fundamentals — the structure decisions that are hardest to reverse.
- Memory usage and heap sizing — what the documented sizing model actually says.
- Hostname and proxy errors — 403s, bad issuers and redirect URI rejections.
- Keycloak vs authentik vs Authelia — choosing between the self-hosted options.
Free tool
Keycloak memory and heap sizing calculator
Turn a peak session count into an Infinispan cache footprint, a per-node JVM heap, the container limit that heap needs, and a node count. Every constant it uses is listed on the page. Runs in the browser, no signup.
Open the calculator