Fission, Knative, or Spin?

Fission if you want functions on Kubernetes. Knative if you want scale-to-zero serving. Spin if the job is Wasm/Workers-shaped. Pick one runtime on day one.

The faas LICENSE puts OpenFaaS Ltd contributions behind a Community Edition EULA for commercial use. This page uses Apache-2.0 runtimes instead.

Coolify is git-push PaaS (/replace/heroku). This page is functions. Different job.

Stacks / Backend

Medium

Fission / Knative Serving

Functions you run. Fission is Apache-2.0 on Kubernetes; Knative Serving is Apache-2.0 scale-to-zero — Cloudflare Workers and AWS Lambda without the invocation meter.

The problem

Cloudflare Workers is a hosted isolate/Wasm runtime. AWS Lambda meters requests and duration. You wanted functions on a cluster you control. Fission is Apache-2.0 (fission/fission). Knative Serving is Apache-2.0 (knative/serving) if you want scale-to-zero on Kubernetes. Spin (spinframework/spin, Apache-2.0) is the Wasm/Workers-shaped sibling; wasmCloud is the CNCF Wasm host. OpenFaaS CE is not the path: the repo LICENSE requires a commercial EULA for commercial use of CE. This is not every Workers KV, Durable Object, or Lambda trigger.

Replaces

Cloudflare Workers / AWS Lambda

Replace Cloudflare Workers Replace AWS Lambda See all best open-source function runtimes

Estimated SaaS saved

$1,200

per year, small team, before lock-in

Start on Railway

Coolify if this is git-push PaaS, not functions

Sponsor this stack Tip jar

Placeholder: Fission and Knative want Kubernetes. Spin can run as a Wasm host on a VM. A single Railway service is often the wrong size — a cluster or a VPS is the honest path. No one-click template in this repo yet — Start on Railway. A git-push PaaS stays on /stacks/coolify-paas.

The stack

Fission
Apache-2.0 serverless functions on Kubernetes
Catalog entry →
Knative Serving
Apache-2.0 scale-to-zero request-driven compute
Catalog entry →
Spin
Apache-2.0 Wasm serverless if the job is Workers-shaped isolates
Catalog entry →

Cost table

You stop paying	Typical / year	Self-host instead
Cloudflare Workers / AWS Lambda (small team)	$1,200	Fission, Knative Serving, or Spin

Agent setup prompt

Replace Cloudflare Workers or AWS Lambda with Fission (Kubernetes functions), Knative Serving (scale-to-zero), or Spin (Wasm).

- Fission/Knative: a cluster you already run. Spin: follow spinframework.dev on a VM if you want Wasm.
- Port one function. Do not claim Workers KV, Durable Objects, or every Lambda event source. Write AGENT_PROMPT.md.
- OpenFaaS CE is not the OSS path (commercial EULA for CE commercial use).

Also as markdown: /stacks/fission-functions.md

FAQ

Fission, Knative, or Spin?: Fission if you want functions on Kubernetes. Knative if you want scale-to-zero serving. Spin if the job is Wasm/Workers-shaped. Pick one runtime on day one.
Why not OpenFaaS?: The faas LICENSE puts OpenFaaS Ltd contributions behind a Community Edition EULA for commercial use. This page uses Apache-2.0 runtimes instead.
Is this Coolify?: Coolify is git-push PaaS (/replace/heroku). This page is functions. Different job.