What is Cortex used for?

Cortex is a horizontally scalable, multi-tenant, long-term storage backend for Prometheus and OpenTelemetry metrics, written in Go. It is a good fit for long-term Prometheus metrics retention, shared metrics platform for multiple teams and scaling Prometheus beyond one server.

Is Cortex open source?

Yes. Cortex is open source under the Apache-2.0 licence. Its source code is on GitHub at cortexproject/cortex and is written mainly in Go.

Yes. Cortex is open source, so the software itself is free to use.

Can I self-host Cortex?

Yes. Cortex can be self-hosted on your own server or infrastructure.

What are some alternatives to Cortex?

Similar open-source tools in the Monitoring & Observability category include VictoriaMetrics, Thanos and Prometheus. SaaS products in the same category include Chronosphere, Amazon CloudWatch and Azure Monitor.

Is Cortex actively maintained?

Yes. The most recent commit to Cortex was on 2 October 2026, and the latest release is v1.21.1, published on 5 June 2026. The project has 5.9k stars on GitHub.

Cortex: open-source monitoring & observability

About Cortex

Cortex is a storage and query layer for metrics that extends Prometheus beyond what a single server can handle. It runs as a cluster spread over several machines, which lets it go past the throughput and storage limits of a single node, and it replicates data between machines when run as a cluster so metrics remain available if a node fails.

A key feature is multi-tenancy: Cortex isolates data and queries from several independent Prometheus sources within a single cluster. It supports long-term storage of metric data on S3, GCS, Swift and Microsoft Azure object storage, and handles both Prometheus and OpenTelemetry metrics. The project is a CNCF project, and its documentation covers architecture, configuration, guides and security.

Cortex is licensed under Apache-2.0 and is run by you, typically on Kubernetes. It suits platform teams and service providers that need shared, durable, scalable metrics storage for many teams or customers.

Key features

Horizontally scalable metrics storage
Replication for high availability
Multi-tenant data and query isolation
Long-term storage on S3, GCS, Swift and Azure
Prometheus and OpenTelemetry metrics support
Runs on Kubernetes clusters

Good fit for

→Long-term Prometheus metrics retention
→Shared metrics platform for multiple teams
→Scaling Prometheus beyond one server

Built with: Go; Kubernetes
Tags: prometheus; metrics; monitoring; multi-tenant; kubernetes; cncf; observability; golang

Cortex: questions and answers

What is Cortex used for?: Cortex is a horizontally scalable, multi-tenant, long-term storage backend for Prometheus and OpenTelemetry metrics, written in Go. It is a good fit for long-term Prometheus metrics retention, shared metrics platform for multiple teams and scaling Prometheus beyond one server.
Is Cortex open source?: Yes. Cortex is open source under the Apache-2.0 licence. Its source code is on GitHub at cortexproject/cortex and is written mainly in Go.
Is Cortex free?: Yes. Cortex is open source, so the software itself is free to use.
Can I self-host Cortex?: Yes. Cortex can be self-hosted on your own server or infrastructure.
What are some alternatives to Cortex?: Similar open-source tools in the Monitoring & Observability category include VictoriaMetrics, Thanos and Prometheus. SaaS products in the same category include Chronosphere, Amazon CloudWatch and Azure Monitor.
Is Cortex actively maintained?: Yes. The most recent commit to Cortex was on 2 October 2026, and the latest release is v1.21.1, published on 5 June 2026. The project has 5.9k stars on GitHub.