Replace / AWS Lambda
Best free AWS Lambda alternatives (open source, self-hosted) 2026
The best open-source alternative to AWS Lambda is Fission (or Knative Serving) with Spin, self-hosted on Railway. 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.
Estimated save $1,200 a year.
Open the stackStart on Railway
How AWS Lambda compares
| AWS Lambda | Fission / Knative Serving | |
|---|---|---|
| Pricing model | Hosted subscription | Open-source or fair-code license; you pay the host |
| Hosting | Vendor cloud | Self-hosted on Railway or any VPS |
| Rough monthly cost | Public list price not verified this run | Hosting only — no SaaS seat meter in this repo |
- Fission
Apache-2.0 serverless functions on Kubernetes
- Knative Serving
Apache-2.0 scale-to-zero request-driven compute
- Spin
Apache-2.0 Wasm serverless if the job is Workers-shaped isolates
FAQ
- What is the best free open-source AWS Lambda alternative?
- The best open-source alternative to AWS Lambda is Fission (or Knative Serving) with Spin, self-hosted on Railway. 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.
- Is it free?
- The Fission / Knative Serving licenses are open source or fair-code. You still pay hosting (Railway or any VPS) and any APIs the stack calls. There is no AWS Lambda seat or task bill on this path.
- Can I migrate from AWS Lambda?
- Yes. Start with the workflows or data you actually use, then cut over. The Fission / Knative Serving stack page has the agent prompt and the cost table; most teams rebuild the slice that matters and leave old AWS Lambda links until they expire.
- How do I deploy it?
- Open the Fission / Knative Serving stack, copy the agent prompt, and deploy on Railway (one service, PORT, and a volume when the app needs disk). 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.
- What does this replace?
- Cloudflare Workers / AWS Lambda. The published small-team estimate on this stack is $1,200 a year.
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