Develop serverless WebAssembly apps with Spin

Create, build, test, and deploy an app in just a few minutes.

Spin CLI example

Spin is the developer tool for building WebAssembly microservices and web applications

Do more, faster. Pick your favorite language and dive into the important part using Spin's serverless framework. Connect your application to Redis, PostgreSQL, and other data services. And skip the boilerplate.

Choose your language

Spin SDKs are available in Python, Go, JavaScript, Rust, Go and .NET. And all WASI-compatible languages are supported.

Spin SDKs are available in Rust, Go and .NET. And all WASI-compatible languages are supported.

Three commands are all you need

Keep the development loop simple. Create a project with 'spin new'. Build it with 'spin build'. And test it locally with 'spin up'.

Keep the development loop simple. Create a project with 'spin new'. Build it with spin build. And test it locally with spin up.

See it in action on the Cloud

Ready for production? Pushing to the Fermyon Cloud is only a 'spin deploy' away.

Ready for production? Pushing to the Fermyon Cloud is only a 'spin deploy' away.

Build full-stack applications

New Serverless AI
Serverless AI  

Execute inferencing for LLMs directly from serverless apps.

SQLite Database
SQLite Databases

Spin has a built-in database, which is always available - no Ops required.

Key/Value Store
Key/Value Store

Quickly persist data in your apps with Spin's in-built local KV store.

HTTP & Redis Triggers
HTTP & Redis Triggers

Spin has a built-in HTTP web server and pub-sub Redis triggers, routing requests and messages to components.

Relational Database Storage
Relational Database Storage

'Bring your own DB' support for MySQL and PostgreSQL, where you host and manage the database outside of Spin.

Variables & Secrets
Variables & Secrets

Dynamic app variables mean a simpler experience for rotating secrets, updating API endpoints, and more.

frictionless developer experience

Powerful CLI
Powerful CLI

Start, run and deploy projects with ease. Blinking cursor to deployed app in 66 seconds.

Languages & SDKs
Languages & SDKs

Spin works with many, many different languages. all WASI-compatible languages are supported.

Powerful CLI
Local Dev

In-built commands like spin watch and spin doctor simplify the writing and debugging of apps.

Powered by WebAssembly

Wasm logo

Run event-driven Wasm services and web applications.

Secure by Default
Secure by Default

Ensure clear separation of services with sandboxing.

Open Source
Open Source

Open Source code written by long-time OSS contributors.


From blinking cusor to deployed app in less than two minutes

Fermyon Cloud is the easiest way to deploy and manage native WebAssembly applications

A micro-CMS for WebAssembly and Spin

Compiled to WebAssembly, Bartholomew can run in any Spin environment.

Why Fermyon?

The next wave of cloud compute looks like this

Architected to compile and ship your code as Wasm binaries, Fermyon is a lighter, faster and truly serverless cloud. No need to deal with images, OS layers or instance config.

Finally the promise of true sustainable serverless cloud computing is here with Fermyon’s Cloud offering — a platform that allows me to use almost any language, is incredibly easy to use and blazingly fast.”

Federico Dionisi

typical app image


cold starts.

0ms 50ms 100ms 150ms 200ms 250ms

Automatically scales-to-zero

Requests are so fast, services can shut back down seamlessly between requests — minimizing compute consumption.


Secure by

Every Wasm application runs in a secure sandbox — eliminating cross contamination.


Compute less, save more

A lighter, faster, and more efficient model means lower cost and more sustainable for your business and our planet.

We've got you covered.

Not just JavaScript — compile almost any language to Wasm.

Rust, Go, Python, JavaScript, .NET, Ruby, C#

Fermyon’s Spin works with mainstream languages like JS/TS, Python, .NET, Rust, and Go. We adhere to the WASI standard, which means dozens of languages that have support for Wasm can be compiled, built and deployed.

Deploy and run for free

No tricks. You can run apps on Fermyon Cloud without having to worry about an expiration date. You can opt into future, paid upgrades later on if you need to.