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Networking · head to head

OpenVPN vs Prometheus

OpenVPN logo

OpenVPN

Networking

Open source VPN protocol with a commercial Access Server product priced per simultaneous connection

From
Free
Rated
-
Full reviewWebsite
Prometheus logo

Prometheus

Networking

Open source monitoring and alerting toolkit for cloud native environments

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: OpenVPN open source OpenVPN, while free, requires real technical skill to configure, secure and maintain without the Access Server admin layer; Prometheus not suitable for per-request billing as collected data lacks 100% accuracy
  • They diverge on capability: OpenVPN covers Open source core, Prometheus covers Multi-dimensional Data Model.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which OpenVPN and Prometheus actually diverge.

Attributes where OpenVPN and Prometheus differ
AttributeOpenVPNPrometheus
Pricing modelOpen source core is free; Access Server billed per simultaneous connectionopen-source
PlatformsLinux, Windows, macOS, iOS, AndroidLinux, macOS, Windows
FoundedUnknown2015

Identical on both: starting price (Free), free tier (Yes), 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 OpenVPN

  • Open source core
  • Access Server admin UI
  • Per-connection licensing
  • Free tier
  • Cross-platform clients

Only in Prometheus

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

What people use each for

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

OpenVPN

  • A technical team wanting a fully free, self-configured VPN server using the open source protocol without any vendor relationshipnot Prometheus
  • A small business wanting a supported, easier-to-administer VPN server, willing to pay per concurrent connection rather than per employeenot Prometheus
  • An organisation with more staff than typical concurrent VPN usage, since Access Server bills only active simultaneous connections, not total accountsnot Prometheus
  • An IoT or large-scale deployment needing custom Enterprise pricing above 2,000 connectionsnot Prometheus

Prometheus

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

Where each one falls short

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

OpenVPN

  • Open source OpenVPN, while free, requires real technical skill to configure, secure and maintain without the Access Server admin layer
  • Per-connection billing on Access Server means usage spikes, such as an all-hands remote day, can push simultaneous connections over a licensed limit and block new connections until usage drops or the plan is upgraded
  • OpenVPN's traditional hub-and-spoke architecture routes traffic through a central server, unlike mesh VPN tools like Tailscale or NetBird that establish direct peer-to-peer connections where possible, which can add latency
  • Client configuration and certificate management for the open source version is more manual and error-prone than newer VPN tools with zero-config onboarding
  • Access Server pricing above the Growth tier reverts to custom Enterprise quoting, so very large deployments lose the pricing transparency of the lower tiers
  • The protocol's throughput is generally lower than newer kernel-integrated protocols like WireGuard under equivalent conditions, which matters for high-bandwidth use cases

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

Pricing, plan by plan

OpenVPN

Free
  • Access Server FreeFree
    • Up to 2 simultaneous connections
    • All features included
  • Access Server Growth$7/month
    • Per simultaneous connection beyond the free tier
    • Annual billing
  • Access Server Enterprise/IoT$undefined/month
    • Custom pricing for 2,000+ connections

Prometheus

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

Which should you pick?

Choose OpenVPN if

  • You need open source core.
  • You want to start without paying.
  • You work on Linux, Windows, macOS, iOS, Android.
  • You also want access server admin ui.
OpenVPN review

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

Questions people ask

Is OpenVPN or Prometheus better?
Neither clearly leads. OpenVPN starts at Free and Prometheus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, OpenVPN or Prometheus?
OpenVPN starts at Free and Prometheus at Free.
Does OpenVPN or Prometheus run on more platforms?
OpenVPN runs on Linux, Windows, macOS, iOS, Android. Prometheus runs on Linux, macOS, Windows.
Can I use OpenVPN for free?
Both have a free tier, so you can try either at no cost before committing.
What is OpenVPN best used for?
OpenVPN is most often used for a technical team wanting a fully free, self-configured vpn server using the open source protocol without any vendor relationship, a small business wanting a supported, easier-to-administer vpn server, willing to pay per concurrent connection rather than per employee, an organisation with more staff than typical concurrent vpn usage, since access server bills only active simultaneous connections, not total accounts, an iot or large-scale deployment needing custom enterprise pricing above 2,000 connections. Of those, a technical team wanting a fully free, self-configured vpn server using the open source protocol without any vendor relationship and a small business wanting a supported, easier-to-administer vpn server, willing to pay per concurrent connection rather than per employee are not what Prometheus is typically brought in for.
What can OpenVPN do that Prometheus cannot?
OpenVPN covers Open source core, Access Server admin UI, Per-connection licensing, Free tier. Prometheus covers Multi-dimensional Data Model, PromQL Query Language, Pull-based Collection, Service Discovery.

Answered from the vendors’ own pages

OpenVPN: Is OpenVPN free?

The open source protocol and software are free under the GPL; Access Server, the commercial packaged product, charges per simultaneous connection beyond a free 2-connection tier.

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
OpenVPN: What counts as a connection for billing purposes?

A simultaneously active connected device, not a registered user account or total device count; unlimited accounts and devices can be created but only the licensed number can be connected at once.

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
OpenVPN: How does OpenVPN compare with WireGuard-based tools like Tailscale?

OpenVPN uses a traditional hub-and-spoke VPN architecture rather than the mesh, peer-to-peer approach used by newer tools like Tailscale or NetBird.

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
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