In simple English
This tool lets you run small pieces of code on demand. It packs each function inside a Docker (a way to run a program inside its own sealed box, so it cannot break anything else on your server) container. You can trigger these functions with webhooks (automated messages sent from one app to another when an event happens). You run it on your own server. It costs you only the price of your server time.
What it is
Fn is an open-source, container-native serverless platform written in Go (a compiled programming language built by Google). It manages the lifecycle of your functions from deployment to execution.
What it is good for
Solo builders who want to host small backend tasks, scheduled jobs, or webhooks without paying for proprietary cloud services like AWS Lambda.
- Runs any Docker container as a function, so you are not locked into specific runtimes.
- Supports multiple programming languages including Go, Python, Node, and Java.
- Can be run locally for development without pushing images to a remote registry.
- Requires Docker (a way to run a program inside its own sealed box, so it cannot break anything else on your server) to be installed and running on your host machine.
- Setup can be tricky on Windows or when using Podman due to socket and volume mounting requirements.
- Lacks a major code update recently, meaning you may encounter unmaintained dependencies.
AWS Lambda
Docker
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curl -LSs https://raw.githubusercontent.com/fnproject/cli/master/install | sh fn start