Softwr

Networking · head to head

Prometheus vs Splunk

Prometheus logo

Prometheus

Networking

Open source monitoring and alerting toolkit for cloud native environments

From
Free
Rated
-
Full reviewWebsite
Splunk logo

Splunk

Networking

Turn Data Into Doing

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only Prometheus has a free tier, so it costs nothing to try first.
  • Each has a real cost: Prometheus not suitable for per-request billing as collected data lacks 100% accuracy; Splunk no prices are published on any plan; every model requires contacting sales for an estimate
  • They diverge on capability: Prometheus covers Multi-dimensional Data Model, Splunk covers Log aggregation.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Prometheus and Splunk actually diverge.

Attributes where Prometheus and Splunk differ
AttributePrometheusSplunk
Starting priceFreeOn request
Pricing modelopen-sourcequote
Free tierYesNo
PlatformsLinux, macOS, WindowsWeb, Api
Founded20152003

Identical on both: user rating (Not yet rated), category (Networking).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Prometheus

  • Multi-dimensional Data Model
  • PromQL Query Language
  • Pull-based Collection
  • Service Discovery
  • Alerting Rules
  • Federation
  • Local Storage
  • Grafana

Only in Splunk

  • Log aggregation
  • Real-time monitoring
  • Data visualization
  • Full-text search
  • Custom dashboards
  • Alert management
  • Anomaly detection
  • Log parsing

What people use each for

The jobs each tool is most often brought in to do.

Prometheus

  • Monitoring and alerting systemnot Splunk
  • Time-series databasenot Splunk
  • Infrastructure metrics collectionnot Splunk

Splunk

  • Log search and analysis across infrastructurenot Prometheus
  • SIEM, SOAR and UEBA for a security operations teamnot Prometheus
  • Application performance and infrastructure monitoringnot Prometheus
  • Cloud, private cloud or on-premises deploymentnot Prometheus

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Prometheus

  • Not suitable for per-request billing as collected data lacks 100% accuracy
  • Hard limit on scrape body size; large responses cause scrape failure
  • Per-scrape sample limit enforced; exceeding limit marks targets as failed
  • Not designed for long-term durable storage; optimised for metrics collection

Splunk

  • No prices are published on any plan; every model requires contacting sales for an estimate
  • Three separate pricing models, workload, ingest and entity, so the same deployment costs different amounts depending on which was signed
  • Ingest pricing bills on data volume, so cost tracks how much you log rather than how much value you get from it
  • Security, observability and platform are priced separately

Pricing, plan by plan

Prometheus

Free
  • Prometheus (Open Source)Free
    • 100% open source
    • Community-driven project
    • Apache 2 License

Splunk

On request
  • Observability Cloud - Infrastructure$15/month
    • Infrastructure monitoring for per host/month pricing
    • Unlimited users and ability to scale to petabytes of data
  • Observability Cloud - App & Infra$60/month
    • App and infrastructure monitoring for per host/month pricing billed annually
  • Observability Cloud - End-to-End$75/month
    • End-to-end observability for per host/month pricing billed annually
  • On-Call$5/month
    • On-call management for per user per month pricing billed annually
    • Covers up to 10 seats

Which should you pick?

Choose Prometheus if

  • You need multi-dimensional data model.
  • You want to start without paying.
  • You work on Linux, macOS, Windows.
  • You also want promql query language.
Prometheus review

Choose Splunk if

  • You need log aggregation.
  • You work on Web, Api.
  • You also want real-time monitoring.
Splunk review

Questions people ask

Is Prometheus or Splunk better?
Neither clearly leads. Prometheus starts at Free and Splunk at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Prometheus or Splunk?
Prometheus has a free tier; the other does not. Paid plans start at Free for Prometheus and On request for Splunk.
Does Prometheus or Splunk run on more platforms?
Prometheus runs on Linux, macOS, Windows. Splunk runs on Web, Api.
Can I use Prometheus for free?
Yes. Prometheus has a free tier, so you can try it without paying. Splunk starts at On request.
What is Prometheus best used for?
Prometheus is most often used for monitoring and alerting system, time-series database, infrastructure metrics collection. Of those, monitoring and alerting system and time-series database are not what Splunk is typically brought in for.
What can Prometheus do that Splunk cannot?
Prometheus covers Multi-dimensional Data Model, PromQL Query Language, Pull-based Collection, Service Discovery. Splunk covers Log aggregation, Real-time monitoring, Data visualization, Full-text search.

Answered from the vendors’ own pages

Prometheus: What does Prometheus cost?

Prometheus is completely free and open source. There are no pricing tiers or paid plans. The entire project is licensed under Apache 2 and hosted on GitHub.

Source
Splunk: What is Splunk's pricing model?

Splunk offers activity-based, ingest, or workload pricing options depending on the product. Splunk Observability Cloud and AppDynamics use per-host or per-vCPU monthly pricing billed annually. Splunk Cloud Platform and Splunk Enterprise require custom quotes from sales.

Source
Prometheus: Is Prometheus commercial software or free?

Prometheus is 100% open source and community-driven. It is a CNCF graduated project with no commercial restrictions or licensing fees.

Source
Splunk: How much does Splunk Enterprise cost?

Splunk Enterprise pricing requires contact with sales. The vendor offers data-ingest or workload pricing options, supports unlimited users, and can scale to petabytes of data, but specific rates are not published online.

Source
Prometheus: How is Prometheus licensed?

Prometheus is licensed under the Apache 2 License, which permits free use, modification, and distribution for commercial and non-commercial purposes.

Source
Splunk: What are the differences between Splunk's pricing options?

Splunk offers multiple pricing models: ingest-based pricing charges according to data volume brought into the system; workload-based pricing charges based on computing resources consumed by workloads. Both models apply to Splunk Enterprise and Splunk Cloud Platform. Standard support is included with product purchases; premium support is available as an add-on.

Source
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