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Build and run event-driven microservices with WebAssembly for speed and portability.

Free plan available, paid tiers above
FreemiumDeveloper ToolsHosting & DeploymentDevOps
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Tracked since2026

The Bottom Line

Price
Free plan available, paid tiers above. Compare plans

Key facts

  • Builds event-driven microservices with WebAssembly (Wasm).
  • Offers millisecond cold start times and high portability.
  • Supports multiple programming languages and open standards for flexible deployment.

Pros

  • Achieves extremely fast cold start times for applications.
  • Provides a secure and isolated execution environment through Wasm sandboxing.
  • Allows developers to use familiar programming languages with Wasm.
  • Ensures high portability across diverse deployment environments due to open standards.
  • Reduces operational overhead by eliminating the need to keep applications 'warm'.

Cons

  • Requires understanding of WebAssembly concepts for optimal use.
  • As a CNCF sandbox project, it may still be evolving with potential API changes.

What is Spin?

Spin is an open-source framework designed for developing and executing event-driven microservice applications using WebAssembly (Wasm) components. It leverages Wasm's inherent sandboxing, portability, and speed to offer a highly efficient application environment. A key benefit of Spin is its millisecond cold start times, eliminating the need for applications to be kept 'warm' and reducing operational overhead. Spin is built on open standards and supports a wide range of programming languages that compile to Wasm, allowing developers to utilize existing skills without learning new languages or libraries. It provides implementations for various deployment scenarios, including local development, self-hosted servers, Kubernetes, and cloud-hosted services, ensuring flexibility in how applications are deployed and managed. As a Cloud Native Computing Foundation (CNCF) sandbox project, Spin emphasizes cloud-native principles and interoperability.
how we evaluateSourcedeveloper.fermyon.com ↗

Key Features

  • Event-driven microservice architecture
  • WebAssembly (Wasm) component support
  • Sandboxed execution environment
  • Portable application deployment
  • Millisecond cold start times
  • Multi-language support via Wasm implementations
  • Open-source Cloud Native Computing Foundation (CNCF) project
  • Deployment options for local, self-hosted, Kubernetes, and cloud environments

Pricing Plans

Pricing checked Oct 5, 2026

Spin plans and prices, checked October 2026
PlanPriceDetails
Wasm Functions

Free and paid levels

  • Fast and powerful engine for hosting serverless functions
  • Running on Akamai Cloud
  • Distributed cloud platform
Cloud

Free and paid levels

  • Simple way to deploy and run Spin apps on Fermyon’s hosted service
  • Offers free and paid levels, depending on request volume
Platform for Kubernetes

Contact us

  • Enterprise solution for Wasm workloads in Kubernetes
  • In your cloud or on-prem
  • High density, efficient compute
View full pricing

Is Spin worth the price?

Fair value

The 'Platform for Kubernetes' tier requires a 'Contact us' approach, which is typical for enterprise solutions but lacks transparency for initial evaluation.

This structure seems best suited for developers and organizations who are already committed to WebAssembly and are looking for flexible deployment options, with the understanding that costs will scale with usage.

Hidden Costs & Gotchas

Overage fees for 'Cloud' tier usage

Full Spin pricing: every plan, hidden costs and alternatives

Reviews

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Spin FAQ

What are the primary benefits of using WebAssembly with Spin?

WebAssembly provides sandboxing for security, ensures high portability across different systems, and enables millisecond cold start times for applications, eliminating the need to keep them constantly running.

Which programming languages are supported for building Spin applications?

Spin supports many programming languages that have WebAssembly implementations, allowing developers to leverage their existing language expertise without learning new ones.

Where can Spin applications be deployed?

Spin applications are highly portable and can be deployed in various environments, including local development setups, self-hosted servers, Kubernetes clusters, and cloud-hosted services.

Is Spin an open-source project?

Yes, Spin is an open-source project and is part of the Cloud Native Computing Foundation (CNCF) as a sandbox project, built on open standards.

What kind of applications is Spin best suited for?

Spin is ideal for building and running event-driven microservice applications that require fast startup times, secure execution, and high portability.

Source: developer.fermyon.com

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