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Cloud · head to head

Cilium vs K3s

Cilium logo

Cilium

Cloud

eBPF-based networking, observability and security for Kubernetes

From
Free
Rated
-
Full reviewWebsite
K3s logo

K3s

Cloud

Lightweight certified Kubernetes distribution in a single binary

From
Free
Rated
-
Full reviewWebsite

The short version

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

Where they differ

Only the attributes on which Cilium and K3s actually diverge.

Attributes where Cilium and K3s differ
AttributeCiliumK3s
PlatformsKubernetes, LinuxLinux, ARM, Self-hosted

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 Cilium

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

Only in K3s

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

What people use each for

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

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

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

Where each one falls short

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

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

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

Pricing, plan by plan

Cilium

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

K3s

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

Which should you pick?

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

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

Questions people ask

Is Cilium or K3s better?
Neither clearly leads. Cilium starts at Free and K3s at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cilium or K3s?
Cilium starts at Free and K3s at Free.
Does Cilium or K3s run on more platforms?
Cilium runs on Kubernetes, Linux. K3s runs on Linux, ARM, Self-hosted.
Can I use Cilium for free?
Both have a free tier, so you can try either at no cost before committing.
What is Cilium best used for?
Cilium is most often used for kubernetes networking at a scale where iptables-based cni performance degrades, network policy expressed on workload identity rather than fragile ip rules, seeing which services actually talk to each other, and what policy is dropping. Of those, kubernetes networking at a scale where iptables-based cni performance degrades and network policy expressed on workload identity rather than fragile ip rules are not what K3s is typically brought in for.
What can Cilium do that K3s cannot?
Cilium covers eBPF datapath, Identity-based policy, Hubble observability, Sidecar-free mesh. K3s covers Single binary, SQLite by default, Certified conformant, Batteries included.

Answered from the vendors’ own pages

Cilium: Is Cilium free?

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

K3s: Is K3s free?

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

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: Is K3s real Kubernetes?

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

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: 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.

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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