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Cloud · head to head

Caddy vs K3s

Caddy logo

Caddy

Cloud

Web server with automatic HTTPS by default

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: Caddy smaller ecosystem than Nginx, so third-party guides and modules are fewer; 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: Caddy covers Automatic HTTPS, K3s covers SQLite by default.

Where they differ

Only the attributes on which Caddy and K3s actually diverge.

Attributes where Caddy and K3s differ
AttributeCaddyK3s
PlatformsLinux, macOS, Windows, DockerLinux, 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 Caddy

  • Automatic HTTPS
  • Caddyfile
  • Reverse proxy

Only in K3s

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

Both cover

  • Single binary

What people use each for

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

Caddy

  • Sites and services where expired certificates have caused outages beforenot K3s
  • Small deployments where Nginx configuration is more effort than the problem warrantsnot K3s
  • Reverse proxying internal services with TLS without a certificate workflownot K3s

K3s

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

Where each one falls short

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

Caddy

  • Smaller ecosystem than Nginx, so third-party guides and modules are fewer
  • Adding plugins means rebuilding the binary rather than loading a module
  • Under very high throughput Nginx generally still benchmarks ahead
  • Automatic certificate issuance needs outbound internet access, which complicates air-gapped deployments

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

Caddy

Free
  • CaddyFree
    • Full functionality
    • Commercial use permitted
    • Community support

K3s

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

Which should you pick?

Choose Caddy if

  • You need automatic https.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Docker.
  • You also want caddyfile.
Caddy review

Choose K3s if

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

Questions people ask

Is Caddy or K3s better?
Neither clearly leads. Caddy 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, Caddy or K3s?
Caddy starts at Free and K3s at Free.
Does Caddy or K3s run on more platforms?
Caddy runs on Linux, macOS, Windows, Docker. K3s runs on Linux, ARM, Self-hosted.
Can I use Caddy for free?
Both have a free tier, so you can try either at no cost before committing.
What is Caddy best used for?
Caddy is most often used for sites and services where expired certificates have caused outages before, small deployments where nginx configuration is more effort than the problem warrants, reverse proxying internal services with tls without a certificate workflow. Of those, sites and services where expired certificates have caused outages before and small deployments where nginx configuration is more effort than the problem warrants are not what K3s is typically brought in for.
What can Caddy do that K3s cannot?
Caddy covers Automatic HTTPS, Caddyfile, Reverse proxy. K3s covers SQLite by default, Certified conformant, Batteries included, Low resource footprint. Both handle Single binary.

Answered from the vendors’ own pages

Caddy: Is Caddy free?

Yes, open source under the Apache 2.0 licence, free for commercial use.

K3s: Is K3s free?

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

Caddy: What does automatic HTTPS mean?

Caddy obtains certificates from Let’s Encrypt or ZeroSSL on first request and renews them before expiry, with no cron job or configuration.

K3s: Is K3s real Kubernetes?

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

Caddy: Caddy or Nginx?

Caddy is dramatically simpler to configure and removes certificate management. Nginx has the larger ecosystem and better peak throughput.

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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