A fast, free, open-source local cloud service emulator.
Overcast emulates the APIs of popular cloud services so you can develop and test locally — without an internet connection, a cloud account, or a bill.
docker run --rm -p 4566:4566 ghcr.io/overcast-sh/overcast:latest
That is the whole getting-started guide. The AWS API is live on port 4566;
add -p 4567:4567 for the web console.
Every change is tested against eight official AWS clients — the AWS CLI, the CDK, and the Go, JavaScript, Python, Java, .NET, and Rust SDKs.
| Repo | What it is |
|---|---|
| overcast | The emulator itself. |
| examples | Example projects built against Overcast, starting with an AWS CDK app. |
| website | Source for overcast.sh — product pages and documentation. |
| branding | Brand assets, design tokens, and the brand book. |
- overcast.sh — documentation, downloads, and the service compatibility matrix
- brand.overcast.sh — brand guidelines and every asset
- Contributing — how to get involved
MIT licensed. No auth tokens, no telemetry, no usage limits, no feature gates.