K3s is Kubernetes, just packaged small. It's a fully compliant Kubernetes distribution in a single binary under 100 MB that uses about half the memory, so it suits edge devices, home labs, CI and small clusters. K8s, upstream Kubernetes, is the full platform you assemble from separate components, and it's the better fit when you need every choice of datastore, networking and add-on at large scale.
I read the K3s documentation, including its architecture and requirements pages, and the Kubernetes overview on kubernetes.io. The naming joke tells you the whole idea: Kubernetes is a 10-letter word shortened to K8s, so something half the size became K3s.
K3s and K8s compared
| K3s | K8s (Kubernetes) | |
|---|---|---|
| In one line | A lightweight, fully compliant Kubernetes distribution | The upstream open source container orchestration platform |
| Packaging | One binary under 100 MB, or a minimal container image | Separate control plane components you install and wire up |
| Default datastore | SQLite, with etcd, MySQL and Postgres available | Set up as part of the cluster you build |
| Bundled extras | containerd, Flannel, CoreDNS, Traefik ingress, ServiceLB and more | You choose your own network, ingress and storage add-ons |
| Smallest server named | 2 cores and 2 GB RAM; agents 1 core and 512 MB | Depends on the distribution or cloud you pick |
| Typical home | Edge, IoT, home labs, CI, ARM boards, air-gapped sites | Production clusters, run by your team or a provider |
| Free option (as of October 2026) | Yes, K3s is open source | Yes, Kubernetes is open source |
What K3s takes care of for you
The K3s docs list the parts it bundles so a cluster works straight away: the containerd runtime, Flannel for networking, CoreDNS, the Traefik ingress controller, a ServiceLB load balancer, Kube-router for network policy, a local-path storage provisioner and the Spegel image mirror. All control plane pieces run in one process, and the only external needs are a modern kernel and cgroup mounts. K3s bundles Traefik by default, and if that choice does not fit your cluster, there are ingress controllers other than Traefik to compare.
High availability is still on the table. You can run three or more server nodes with embedded etcd, or two or more servers backed by an external MySQL, PostgreSQL or etcd database. The sizing guide says a server with 2 CPUs and 4 GB of RAM handles up to 350 agents, and it asks you to join agents in batches of 50 or less.
Hardware gotchas worth knowing
Here's the line that saves Raspberry Pi projects: the K3s requirements page warns that etcd is write intensive and SD cards and eMMC storage can't handle the load, so it recommends an external SSD on ARM devices. The server also needs port 6443 reachable by every node.
If the cluster will run on your own hardware, my comparison of Hyper-V and Proxmox helps with the hypervisor choice.
What full Kubernetes gives you
The Kubernetes overview describes a portable, extensible platform for containerised workloads, open sourced by Google in 2014 with over 15 years of Google's production experience behind it. Its feature list covers service discovery and load balancing, storage orchestration, automated rollouts and rollbacks, self-healing, secret management, batch jobs and horizontal scaling. K3s passes the same conformance, so your manifests carry over.
The other orchestrator people consider is covered in my comparison of Docker Swarm and Kubernetes.
Picking one in four questions
- Is the cluster on small or remote hardware? K3s was built for that.
- Do you want a working cluster from one install command? K3s bundles the add-ons.
- Does your team need to choose every component, or use a cloud's managed Kubernetes? Go with upstream K8s.
- Unsure? Start on K3s; because it's compliant Kubernetes, what you learn and write transfers.
For the bigger architecture question behind containers, see monolithic vs microservices pros and cons, and these developer productivity tools that earn their place.
If even K3s feels like more than you need, there are lighter options, and my guide to ways to run containers sets them out.
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My advice on K3s or K8s
I'd start with K3s for anything that isn't already headed to a big managed cluster: a home lab, a test environment, a shop-floor device or a small production service. It's still Kubernetes, so you're not learning a dead end. Move to full upstream Kubernetes, or your cloud's managed version, when you need its flexibility at scale or a team that wants to pick every part. And don't run K3s on an SD card if you want it to last. Teams weighing an enterprise platform instead can read how OpenShift differs from Kubernetes.
Do you make a container, cloud or DevOps tool? Tool makers can ask to be considered for a featured place in comparisons like this one.
Frequently asked questions
Is K3s real Kubernetes?
Yes. The K3s docs call it a fully compliant Kubernetes distribution, so standard Kubernetes manifests and tools work with it.
Why is it called K3s?
Kubernetes is a 10-letter word written as K8s. K3s was meant to be half the size, so it became a 5-letter word, K3s. It has no long form.
What hardware does K3s need?
The minimum is 2 cores and 2 GB of RAM for a server node and 1 core with 512 MB for an agent, with an SSD recommended.
Can K3s run in high availability?
Yes, with three or more servers using embedded etcd, or two or more servers with an external MySQL, PostgreSQL or etcd datastore.
Who created Kubernetes?
Google open sourced Kubernetes in 2014, building on over 15 years of running production workloads.
