head to head · open source
authelia vs cas
authelia has 29,482 GitHub stars, 1,531 forks, 137 open issues and last shipped yesterday. cas has 11,394 stars, 3,955 forks, 17 open issues and last shipped yesterday. authelia leads on adoption by 159% (29,482 vs 11,394 stars). authelia is written in Go under Apache-2.0; cas is written in Java under Apache-2.0. authelia has attracted 5% as many forks as stars, cas 35%. authelia was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (authentication, mfa, oauth2), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| authelia | cas | |
|---|---|---|
| GitHub stars | ★ 29K | ★ 11K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Go | Java |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 1.5K | ⑂ 4.0K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick authelia if
- You weight community size — 29K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Go
- You value the larger contributor base for long-term maintenance
pick cas if
- You want the cas feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and cas fits your workflow better
About authelia
<img alt="SLSA 3" src="
read the full authelia overview →
About cas
Central Authentication Service (CAS) [ ][casslack] [ ][cassupport] Introduction Welcome to the home of the [Central Authentication Service project][apereocas], more commonly referred to as CAS. CAS is an enterprise multilingual identity provider and single sign on solution for the web and attempts to be a comprehensive platform for your authentication and authorization needs. CAS is an open and well documented authentication protocol. The primary implementation of the protocol is an open source Java server component by the same name hosted here, with support for a plethora of additional authentication protocols…
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Frequently asked questions
Is authelia or cas more popular?
authelia has 29,482 GitHub stars and cas has 11,394. authelia has the larger community by that measure.
Are authelia and cas free?
Both are open source. authelia is licensed under Apache-2.0 and cas under Apache-2.0. Neither carries a licence fee.
What is the difference between authelia and cas?
authelia is written in Go and cas in Java. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, authelia or cas?
Choose authelia if you want the larger community (29,482 stars) or its Apache-2.0 licence terms. Choose cas if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.