head to head · open source
Prometheus vs cayley
Prometheus has 66,106 GitHub stars, 10,840 forks, 890 open issues and last shipped yesterday. cayley has 15,064 stars, 1,238 forks, 93 open issues and last shipped 22 days ago. Prometheus leads on adoption by 339% (66,106 vs 15,064 stars). Prometheus is written in Go under Apache-2.0; cayley is written in Go under Apache-2.0. Prometheus has attracted 16% as many forks as stars, cayley 8%. Prometheus was the more recently maintained of the two, and both are self-hostable with no licence fee.
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
| Prometheus | cayley | |
|---|---|---|
| GitHub stars | ★ 66K | ★ 15K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Go | Go |
| Last push | 2026-09-17 | 2026-08-27 |
| Forks | ⑂ 11K | ⑂ 1.2K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Prometheus if
- You weight community size — 66K 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 cayley if
- You want the cayley feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Go
- You evaluated both and cayley fits your workflow better
About Prometheus
Prometheus is an open source monitoring system and time series database, part of the Cloud Native Computing Foundation ecosystem. It collects metrics from configured targets at defined intervals, evaluates alerting rules, and visualizes results. Designed for reliability in dynamic environments, it operates without reliance on distributed storage, ensuring each server node functions independently.
read the full Prometheus overview →
About cayley
Cayley is an open source graph database written in Go and released under the Apache 2.0 license. It stores and queries Linked Data, the graph shaped data model standardized by the W3C for the Semantic Web, and its design takes direct inspiration from the graph database that sat behind Google's Knowledge Graph, formerly known as Freebase. The project lives in the Go ecosystem and has been maintained in public for roughly twelve years, accumulating about 15,000 stars and 1,238 forks, with 93 open issues at the time of writing. Its topics — cayley, go, graph, graph database, linked data — describe both the language …
read the full cayley overview →
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Frequently asked questions
Is Prometheus or cayley more popular?
Prometheus has 66,106 GitHub stars and cayley has 15,064. Prometheus has the larger community by that measure.
Are Prometheus and cayley free?
Both are open source. Prometheus is licensed under Apache-2.0 and cayley under Apache-2.0. Neither carries a licence fee.
What is the difference between Prometheus and cayley?
Prometheus is written in Go and cayley in Go. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Prometheus or cayley?
Choose Prometheus if you want the larger community (66,106 stars) or its Apache-2.0 licence terms. Choose cayley if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.