Understand what Prometheus is, how its architecture and PromQL query language work, its pricing model, and how it compares to other monitoring tools in 2026.
Prometheus is an open-source monitoring system and time-series database that originated at SoundCloud in 2012 to solve internal infrastructure-monitoring needs, and was later contributed to the Cloud Native Computing Foundation (CNCF) in 2016 as its second hosted project after Kubernetes. It graduated to CNCF's highest maturity tier in 2018.
There is no company behind Prometheus in the traditional sense; it is maintained by a large open-source community under CNCF governance, and released under the permissive Apache License 2.0, making it free to use, self-host, and modify for any purpose.
Prometheus uses a pull-based scraping model, where the Prometheus server actively collects metrics from configured targets at regular intervals, which fits naturally with dynamic, containerized infrastructure such as Kubernetes clusters. Collected data is stored in an efficient built-in time-series database and queried using PromQL, Prometheus's own powerful query language for filtering and aggregating metrics.
The ecosystem includes client libraries for instrumenting custom application code, and a large catalog of exporters that translate metrics from existing systems like databases, web servers, and operating systems into Prometheus's format. A separate Alertmanager component handles deduplication, grouping, and routing of fired alerts to the right notification channels.
Prometheus itself is completely free, with no licensing cost, usage limits, or paid tiers, since it is open-source software released under the Apache License 2.0.
Organizations that want a managed experience rather than operating Prometheus themselves can pay third-party vendors for managed or Prometheus-compatible hosted monitoring services, but that is a separate commercial layer, not something Prometheus or CNCF sells directly.
Yes, Prometheus is completely free and open source, released under the Apache License 2.0, with no licensing fees or usage limits.
Prometheus originated at SoundCloud in 2012 to address internal infrastructure-monitoring needs, and was later contributed to the Cloud Native Computing Foundation in 2016.
Yes, Prometheus became the second project to reach CNCF's graduated status in August 2018, following Kubernetes.
Prometheus uses PromQL, its own functional query language designed for filtering, aggregating, and performing calculations on time-series metrics data.
Prometheus evaluates alerting rules and fires alerts, and a separate component called Alertmanager handles deduplication, grouping, routing, and silencing of those alerts.
Yes, Prometheus's pull-based scraping and native service discovery make it one of the most widely used monitoring systems for Kubernetes and other cloud-native environments.
No, Prometheus can be used, modified, and deployed commercially at no cost under the Apache License 2.0, since it has no owning company or commercial license requirement.
Exporters are small adapter applications that translate metrics from third-party systems, like MySQL, PostgreSQL, Redis, or NGINX, into the Prometheus metrics format so they can be scraped and monitored.