Networking · head to head
OPNsense vs Splunk
OPNsense
Networking
FreeBSD-based firewall and routing platform with weekly updates and a full configuration API
- From
- Free
- Rated
- -
The short version
- Only OPNsense has a free tier, so it costs nothing to try first.
- Each has a real cost: OPNsense throughput depends entirely on hardware you selected yourself, and intrusion prevention at multi-gigabit rates will saturate a machine that handled plain firewalling fine, with no vendor sizing commitment to fall back on.; Splunk no prices are published on any plan; every model requires contacting sales for an estimate
- They diverge on capability: OPNsense covers Stateful firewall on pf, Splunk covers Log aggregation.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which OPNsense and Splunk actually diverge.
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 OPNsense
- Stateful firewall on pf
- VPN suite
- Suricata IDS and IPS
- Full configuration API
- High availability
- Weekly update cadence
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.
OPNsense
- Replacing a small business firewall appliance whose renewal quote exceeded the cost of the hardwarenot Splunk
- Branch offices where the firewall configuration must be produced by Ansible rather than by handnot Splunk
- Sites that need WireGuard and intrusion prevention on the same box without separate feature licencesnot Splunk
- A homelab or lab network needing VLAN routing, multi-WAN and DNS filtering on one machinenot Splunk
Splunk
- Log search and analysis across infrastructurenot OPNsense
- SIEM, SOAR and UEBA for a security operations teamnot OPNsense
- Application performance and infrastructure monitoringnot OPNsense
- Cloud, private cloud or on-premises deploymentnot OPNsense
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
OPNsense
- Throughput depends entirely on hardware you selected yourself, and intrusion prevention at multi-gigabit rates will saturate a machine that handled plain firewalling fine, with no vendor sizing commitment to fall back on.
- The weekly update cadence is good for security but means more change events than a team used to annual appliance firmware, and occasional regressions reach production installations.
- FreeBSD underneath limits driver support compared with Linux, so recent network cards and some virtualisation drivers can be unsupported or slow.
- The plugin ecosystem is uneven in quality; some plugins are maintained by a single contributor and can lag a major release, breaking a function you depended on.
- Community support is a forum, so an outage at two in the morning on the free edition is your problem alone unless you bought the business subscription in advance.
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
OPNsense
Free- OPNsense Community EditionFree
- MIT licence with no feature restrictions
- All VPN, IDS and HA features included
- Weekly updates and two major releases a year
- OPNsense Business Edition$undefined/year
- Stabilised update track lagging community releases
- Commercial support from Deciso
- Additional enterprise plugins and configuration backup
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 OPNsense if
- You need stateful firewall on pf.
- You want to start without paying.
- You work on x86-64 appliances, Virtual machines, Deciso hardware.
- You also want vpn suite.
Choose Splunk if
- You need log aggregation.
- You work on Web, Api.
- You also want real-time monitoring.
Questions people ask
- Is OPNsense or Splunk better?
- Neither clearly leads. OPNsense 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, OPNsense or Splunk?
- OPNsense has a free tier; the other does not. Paid plans start at Free for OPNsense and On request for Splunk.
- Does OPNsense or Splunk run on more platforms?
- OPNsense runs on x86-64 appliances, Virtual machines, Deciso hardware. Splunk runs on Web, Api.
- Can I use OPNsense for free?
- Yes. OPNsense has a free tier, so you can try it without paying. Splunk starts at On request.
- What is OPNsense best used for?
- OPNsense is most often used for replacing a small business firewall appliance whose renewal quote exceeded the cost of the hardware, branch offices where the firewall configuration must be produced by ansible rather than by hand, sites that need wireguard and intrusion prevention on the same box without separate feature licences, a homelab or lab network needing vlan routing, multi-wan and dns filtering on one machine. Of those, replacing a small business firewall appliance whose renewal quote exceeded the cost of the hardware and branch offices where the firewall configuration must be produced by ansible rather than by hand are not what Splunk is typically brought in for.
- What can OPNsense do that Splunk cannot?
- OPNsense covers Stateful firewall on pf, VPN suite, Suricata IDS and IPS, Full configuration API. Splunk covers Log aggregation, Real-time monitoring, Data visualization, Full-text search.
Answered from the vendors’ own pages
OPNsense: How is it different from pfSense?
It is a 2015 fork with an MIT licence, a fixed weekly release cadence, a complete configuration API and a different interface. Feature coverage is comparable; the release process and API are the real differences.
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.
SourceOPNsense: Do I need the Business Edition?
Only if you want commercial support or a slower, stabilised update stream. No features are withheld from the community edition.
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.
SourceOPNsense: Can it handle a gigabit internet connection?
Plain firewalling on modest current hardware, comfortably. With Suricata inspection enabled, expect to need a considerably stronger CPU.
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.
SourceRelated pages
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