head to head · open source
Prometheus vs cayley
Prometheus has 66,906 GitHub stars, 10,969 forks, 890 open issues and last shipped yesterday. cayley has 15,067 stars, 1,234 forks, 93 open issues and last shipped 2 months ago. Prometheus leads on adoption by 344% (66,906 vs 15,067 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 | ★ 67K | ★ 15K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Go | Go |
| Last push | 2026-11-02 | 2026-08-27 |
| Forks | ⑂ 11K | ⑂ 1.2K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Prometheus if
- You weight community size — 67K 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 Visit prometheus.io for the full documentation, examples and guides. [ ][quay] [ ][hub] Prometheus, a Cloud Native Computing Foundation project, is a systems and service monitoring system. It collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts when specified conditions are observed. The features that distinguish Prometheus from other metrics and monitoring systems are: A multi dimensional data model (time series defined by metric name and set of key/value dimensions) PromQL, a powerful and flexible query language to…
read the full Prometheus overview →
About cayley
Cayley is an open source database for Linked Data. It is inspired by the graph database behind Google's Knowledge Graph (formerly Freebase)). Documentation Features Built in query editor, visualizer and REPL Multiple query languages: Gizmo: query language inspired by Gremlin GraphQL inspired query language MQL: simplified version for Freebase) fans Modular: easy to connect to your favorite programming languages and back end stores Production ready: well tested and used by various companies for their production workloads Fast: optimized specifically for usage in applications Performance Rough performance testing…
read the full cayley overview →
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Frequently asked questions
Is Prometheus or cayley more popular?
Prometheus has 66,906 GitHub stars and cayley has 15,067. 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 (66,906 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.