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Cloud · head to head

K3s vs Cilium

K3s logo

K3s

Cloud

Lightweight certified Kubernetes distribution in a single binary

From
Free
Rated
-
Full reviewWebsite
Cilium logo

Cilium

Cloud

eBPF-based networking, observability and security for Kubernetes

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: K3s the SQLite default is single-server only; highly available control planes need etcd or an external datastore, which removes much of the simplicity; Cilium requires a recent Linux kernel, which rules out older distributions and some managed environments
  • They diverge on capability: K3s covers Single binary, Cilium covers eBPF datapath.

Where they differ

Only the attributes on which K3s and Cilium actually diverge.

Attributes where K3s and Cilium differ
AttributeK3sCilium
PlatformsLinux, ARM, Self-hostedKubernetes, Linux

Identical on both: starting price (Free), pricing model (Open source, no licence fee), free tier (Yes), user rating (Not yet rated), category (Cloud).

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 K3s

  • Single binary
  • SQLite by default
  • Certified conformant
  • Batteries included
  • Low resource footprint
  • Simple install

Only in Cilium

  • eBPF datapath
  • Identity-based policy
  • Hubble observability
  • Sidecar-free mesh

What people use each for

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

K3s

  • Kubernetes on edge sites and IoT hardware where full clusters will not fitnot Cilium
  • Development and CI clusters that must start fast and cost nothingnot Cilium
  • Small production clusters where full Kubernetes is more operations than the workload justifiesnot Cilium
  • Teaching and learning Kubernetes without cloud spendnot Cilium

Cilium

  • Kubernetes networking at a scale where iptables-based CNI performance degradesnot K3s
  • Network policy expressed on workload identity rather than fragile IP rulesnot K3s
  • Seeing which services actually talk to each other, and what policy is droppingnot K3s

Where each one falls short

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

K3s

  • The SQLite default is single-server only; highly available control planes need etcd or an external datastore, which removes much of the simplicity
  • Bundled components such as Traefik are opinionated defaults that larger teams often strip out and replace
  • Removed in-tree cloud provider integrations mean cloud-specific features need external controllers
  • Aimed at small and edge clusters, so very large deployments are better served by a standard distribution

Cilium

  • Requires a recent Linux kernel, which rules out older distributions and some managed environments
  • eBPF is genuinely hard to debug when it misbehaves, and the skill is rare on most teams
  • Broad scope — CNI, policy, mesh, observability — means the learning curve covers several domains at once

Pricing, plan by plan

K3s

Free
  • K3sFree
    • Full functionality
    • No usage limits
    • Community support

Cilium

Free
  • CiliumFree
    • Full functionality
    • No usage limits
    • Community support

Which should you pick?

Choose K3s if

  • You need single binary.
  • You want to start without paying.
  • You work on Linux, ARM, Self-hosted.
  • You also want sqlite by default.
K3s review

Choose Cilium if

  • You need ebpf datapath.
  • You want to start without paying.
  • You work on Kubernetes, Linux.
  • You also want identity-based policy.
Cilium review

Questions people ask

Is K3s or Cilium better?
Neither clearly leads. K3s starts at Free and Cilium at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, K3s or Cilium?
K3s starts at Free and Cilium at Free.
Does K3s or Cilium run on more platforms?
K3s runs on Linux, ARM, Self-hosted. Cilium runs on Kubernetes, Linux.
Can I use K3s for free?
Both have a free tier, so you can try either at no cost before committing.
What is K3s best used for?
K3s is most often used for kubernetes on edge sites and iot hardware where full clusters will not fit, development and ci clusters that must start fast and cost nothing, small production clusters where full kubernetes is more operations than the workload justifies, teaching and learning kubernetes without cloud spend. Of those, kubernetes on edge sites and iot hardware where full clusters will not fit and development and ci clusters that must start fast and cost nothing are not what Cilium is typically brought in for.
What can K3s do that Cilium cannot?
K3s covers Single binary, SQLite by default, Certified conformant, Batteries included. Cilium covers eBPF datapath, Identity-based policy, Hubble observability, Sidecar-free mesh.

Answered from the vendors’ own pages

K3s: Is K3s free?

Yes. K3s is open source with no licence fee. SUSE sells commercial support around Rancher separately.

Cilium: Is Cilium free?

Yes, open source and CNCF-graduated. Isovalent sells an enterprise distribution and support.

K3s: Is K3s real Kubernetes?

Yes. It is CNCF-certified conformant, so standard manifests, kubectl and Helm charts work without modification.

Cilium: What does eBPF change?

It lets Cilium run packet-processing programs inside the kernel instead of relying on iptables rule chains, which behave poorly as the number of services grows.

K3s: Why is K3s smaller than Kubernetes?

It strips legacy, alpha and in-tree cloud provider code, packages everything as one binary, and defaults to SQLite instead of etcd.

Cilium: Does Cilium replace a service mesh?

It can cover much of what a mesh does without sidecars, though full mesh feature sets still favour Istio or Linkerd.

K3s: Can K3s run in production?

Yes, and it does, particularly at the edge and for small clusters. For a highly available control plane you need to move off the SQLite default to etcd or an external datastore.

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