Identity and SSO
Open-source alternatives to Clerk, priced
3 open-source tools that can replace Clerk, each shown with what it would actually cost to run for a team of 10 people. Clerk on the Pro tier costs $25.00 a month at that size.
The cheapest way to replace Clerk here is Keycloak, at $121 a month against $25.00, with your own time already counted.
Start here
Clerk's Hobby plan is free for up to 50,000 monthly retained users. An internal team will almost never exceed that, so for most readers the honest licence cost is zero and the paid comparison below only applies if you need what Pro adds.
| Tool | Server only | With your time | vs Clerk | Operational weight | Licence |
|---|---|---|---|---|---|
| Keycloak | $8.04 | $121 | -$3,889 | medium | Apache-2.0 |
| authentik | $8.04 | $121 | -$3,889 | medium | source-available |
| Zitadel | $8.04 | $121 | -$3,889 | medium | AGPL-3.0 |
The final column is the 36-month difference: positive means self-hosting is cheaper.
Which one to pick
Keycloak 36,732 stars
JVM service with PostgreSQL. Memory is dominated by the heap rather than by user count, so cost per user falls steeply as the directory grows. This is the CNCF-backed incumbent.
At 10 people it needs 2.5 GB of memory and 10.1 GB of disk, which fits the CX23 (cost-optimized) at Hetzner Cloud for $6.70 a month. Setting it up is roughly 6 hours of work, then 1.5 hours a month to keep it healthy.
Full Clerk versus Keycloak breakdown · Keycloak at every team size
authentik 25,446 stars
Server plus worker, PostgreSQL and Redis. Friendlier than Keycloak for proxy-style protection of apps that have no native SSO support.
At 10 people it needs 2.5 GB of memory and 10.1 GB of disk, which fits the CX23 (cost-optimized) at Hetzner Cloud for $6.70 a month. Setting it up is roughly 6 hours of work, then 1.5 hours a month to keep it healthy.
Full Clerk versus authentik breakdown · authentik at every team size
Zitadel 15,005 stars
Go binary over PostgreSQL, with an event-sourced audit log. Lighter than the JVM option and closer to Auth0's developer ergonomics.
At 10 people it needs 2.5 GB of memory and 10.1 GB of disk, which fits the CX23 (cost-optimized) at Hetzner Cloud for $6.70 a month. Setting it up is roughly 6 hours of work, then 1.5 hours a month to keep it healthy.
Full Clerk versus Zitadel breakdown · Zitadel at every team size
How the pricing was established
Clerk pricing was read from its own pricing page on 2026-09-14. Server prices come from the providers listed on the hosting page. The sizing model and the cost of your time are set out in full on the methodology page.
Related
- All identity and sso compared
- Alternatives to Auth0
- Alternatives to Okta Workforce Identity
- Where to host it
What you would be running
| Tool | Licence | Written in | Setup | Upkeep | GitHub stars |
|---|---|---|---|---|---|
| Keycloak | Apache License 2.0 | Java | 6 h | 1.5 h a month | 36,732 |
| authentik | Other | Python | 6 h | 1.5 h a month | 25,446 |
| Zitadel | GNU Affero General Public License v3.0 | Go | 6 h | 1.5 h a month | 15,005 |
Questions people actually ask
Is there a free open-source alternative to Clerk?
There are 3 on this page. 2 of them are open source, published under AGPL-3.0, Apache-2.0, with no licence to buy. authentik ships its source under its own licence rather than a standard open-source one, so check its terms before commercial use. None of them is free to run: the cheapest, Keycloak, costs $121 a month at 10 people once the server, backups and the time to look after it are counted.
How much does Clerk cost?
Clerk Pro costs $25.00 a month at 10 people: USD 25.00 per month. That figure was read from the vendor's own pricing page on 2026-09-14.
What does it cost to self-host Keycloak?
$121 a month at 10 people. That is $6.70 for the CX23 (cost-optimized) at Hetzner Cloud, plus backups, plus 1.5 hours a month of your own time priced at the published hourly rate.
How long before Keycloak is cheaper than Clerk?
Never, counting $450 of first-time setup. Over 36 months the difference is $3,889.
Which Clerk alternative is the easiest to run?
Keycloak, rated medium: about 6 hours to set up and 1.5 hours afterwards.